Introduction to the drama and some basic explanation.

Each Sword and Fairy series has a theme. The Theme of The Legend of the Sword and the Fairy 4 — Pilgrimage(寻仙)

Introduction: (Qionghua Sect 19 years ago, narrated by Yun Tianqing)

The demons were rampant and the people were suffering. Qionghua Sect, the head of the Kunxu eight sects, that has been short of manpower and material resources for three generations, finally made the Wangshu and Xihe swords, the Yin Yang double swords.

19 years ago, the 24th Grandmaster Immortal Tai Qing wanted to use both swords to trap the Huanming Demon Realm. The war was protracted. At the critical moment, Su Yu, the host of Wangshu sword, was bewitched and suddenly withdrew the sword, causing the Wangshu sword's pillar to collapse instantly. Xihe sword couldn't withstand it alone, and it's host Xuan Xiao suffered the backfire of the sword's red aura. Grandmaster Tai Qing died in the battle and Qionghua sect was greatly undermined.

I, Yun Tianqing, a disciple, defected with Su Yu. Since then, Wangshu sword's whereabouts has been unknown.

Based on the introduction some thoughts 

Su Yu is Yun Tianhe's mother, she is enshrined in an translucent ice coffin in Shichengxi cave where later Yun Tianhe's father, Yun Tianqing also lies alongside Su Yu in the same coffin a few years later. 

Su Yu was the host of Wangshu sword that was kept in Shichengxi cave. In episode 1, Tianhe presumably became it's new host due to his yin yang body. The aura of Wangshu sword is extremely cold not many people can withstand the cold and their body parts that touch the sword gets frost bitten. It was later revealed that Wangshu sword also absorbs the holder's spiritual energy in it. 

When Tianhe accidentally becomes the new host, it resonates with the other sword Xihe sword whose aura is extremely hot almost fiery. Xihe sword's host who had been in a coma after the backlash (sealed inside Xuan ice cover in a secluded cave with Xihe sword nearby), wakes up due to the resonant effect of Xihe sword in his cave. (Suyu, the host of Wangshu Sword, abandoned the sect during the war 19 years ago. As a result, Yihe Sword's host, Xuanxiao, loses control of his rampaging Qi and Gong, forcing the sect leader to seal him inside an ice cave. Nineteen years later, Xuanxiao broke the seal with the help of Su Yu's son). Xuan Xiao, the host of Xihe sword apparently had strong feelings for Tianhe's mother, Su Yu who was the host of Wangshu sword. 

After the death of 24th Grandmaster Immortal Tai Qing, Su Yao became the new Grandmaster of Qionghua Sect. She has other other Zao jade piece that is red in colour, probably belongs to Xuan Xiao(one white Zao jade piece it's twin belonged to Su Yu, now with Tianhe). Xuan Xiao dislikes her having the jade piece, Su Yao apparently loves Xuan Xiao but he doesn't return her feelings. 

Qionghua Sect, probably blames Su Yu,  Xuan Xiao and Yun Tianqing for the death of 24th Grandmaster master immortal Tai Qing and the great losses they suffered due to the swords' imbalance caused by Su Yu. 

The Qionghua sect under the guidance of Xuantian Goddess, created the method of cultivating immortality by allowing humans to be one with the sword. Only Qionghua sect can be the leader among kunxu's eight sects and be respected by the people in the world.  Qionghua can kill demons with Three-foot sword.

(As per Su Yao in Episode 24) Huanming Realm is like a star.  It travels along a fixed trajectory. Every 19 years, it will be above Kunxu Qionghua. 19  years ago, Huanming Demon clan used purple crystals' spiritual energy as a bridge to enter the mortal world and slaughter the people. That was why Qionghua Sect had a fierce battle with Huanming Demon clan. In which Quonghua sect suffered massive casualties and ultimately lost the battle. 

Fun facts:

The names of four playable characters in the Role playing games of  The Legend of Sword and Fairy 4 came from mineral ores. These characters are often sported wearing clothes of the colour representing their name colours. 

The name Tianhe comes from amazonite.
The name Lingsha comes from cinnabar.
The name Mengli comes from lapis lazuli.
The name Ziying comes from amethyst.

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Age of Four main characters as per the game.
Liu Mengli - 20
Yun Tianhe - 18
Han Lingsha -17
Murong Ziying - 19 -119(ending)

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Race/ Occupation/ Weapons of Four main characters as per the game.
Liu Mengli - Monster/Queen of Dreams/Konghou Zither
Yun Tianhe - Human/ Hunter/ Sword & Bow
Han Lingsha - Human/ Tomb Raider/Twin spike & Twin Sword
Murong Ziying - Human/ Sword Master/ Sword

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Fascinating objects/ artifacts/ creations mentioned. 

Episode 1 - Han Ling Sha's red bag,  Qiankun bag (episode 12 named) seems like it has every item that she might need, I had read about such bags in a fantasy story where the bag was attached to an abyss and could store and summon any item required.

Episode 7 - Mengli presents Tianhe with a bow to replace the bow that was broken during her illusion trap. This jade bow is made from a 1000- year dragon scale. The bow string is made from Tianshan ice silk. 

Episode 7 - Lixiang herb sachet given by Mrs Liu to Mengly when she leaves the Liu residence, it smells stronger the further away you are from home. The  song sung by children for that herb  "Lixiang herb is a home away from your home. Don't forget your luggage when you leave. I hope you remember with this fragrance. When the fragrance dissipates,  you're back at your home town. Lixiang herb is a home away from your home."

Episode 9- Beike from Huanming demon clan stole Li Jiangliu's Qiankun beads and combined them with 3000 Primordial spirits to make the spirit armour that could destroy Wangshu sword.

Episode 12 - Fuyao Immortal Fruit Elixir to cure all illnesses was given to Han Lingsha. (Although the series mentions many pills and elixirs, I found this one the most interesting) 

Episode 13- Princess Jade the green stone in ar Mengli's necklace. Given to her by Su yu and  Yun Tian Qing for her protection. Princess jade originates from an ancient, magical jade. The one wearing it,  will be full of spiritual power. It can repel all kinds of evil. (Ep 27 The demon who wears this can suppress its demonic aura and be indistinguishable from humans)

Episode 17-  forging of divine swords (Yin -Yang swords)Wangshu and Xihe, The Qionghua sect forged the divine swords with the secret sword forging technique of their sect. They obtained the Pure wave stone from the bottom of the east sea. The moonlight jade from under Heavenly mountain Ice pool, and combine it with ancient spiritual wood from the northwestern wilderness. It took three generations to complete the forging along with resource, it started with Dan Yin and was completed by Zong Lian. After the sword is completed,  it still needs to acknowledge its host. Doing so releases its powerful force. 

Episode 19 - the background of Xuan Ying was disclosed by Su Yao in episode 19. She said because she could not get over Xuan Xiao, she created a shadow puppet, Xuan Ying who looks the same as Xuan Xiao. Xuan Ying is Xuan Xiao's shadow.  Su Yao says Xuan Ying is a shell that doesn't have a heart or senses. He is not a real man. He is just Xuan Xiao's substitute. He doesn't have a heartbeat so doesn't deserve to have emotions.  He needed  primordial spirits of humans to survive (Xuan Ying was more human than some of the 'righteous' characters in the series) 

Episode 23- Suoluo fruit's spiritual power needed to be injected into Xuan Xiao. Tianhe who could withstand extreme cold held the fruit to ease Xuan Xiao's pain and bring him back to consciousness after Xuan Xiao's battle with elder ChongGuang. Elder Zong Lian who along with others had imprisoned Xuan Xiao in Xuan ice found a way to break the ice out of compassion for Xuan Xiao. Zong Lian found 3 cold weapons to break the ice. Suoluo fruit, kunlin and the third unknown object. Yun TianQing and Zong Lian found Suolou fruit in the Emperor Yan Shennong cave. Zong Lian made a container of warm red jade using up 30% of his spiritual cultivation to bring the extremely cold Suolou fruit back to the Qionghua sect. 

Episode 24- second cold weapon to break Xuan ice is Kun Scale. It is a scale that fell off Northern Kun fish where it transformed into a roc. No one knows its whereabouts. The third cold weapon as identified by Lingsha is the Guangji Cold Painting. It appears when there is a phenomenon of stars descending to the mortal world and the Milky Way hanging upside down. It is by the sea. 

Episode 26- A divine bow is given to Tianhe. The divine bow is called the Primordial-Spirit-Initiating, Moon-Chasing Bow. "Primordial-Spirit-Initiating" represents not regretting the original Intention. "Moon-chasing" Represents not being afraid of moving forward. (More about) Guangji Cold Painting made by northern black emperor can turn back time and change the trajectory of life.

Episode 31-  Tianhe fights the divine dragon to enter the Netherworld to get the barrier crossing branch with which they could enter Huanming Realm to check on Mengli. The divine dragon guarding the Buzhou mountain suggests that Tianhe should obtain the Hou Yi's sun shooting bow kept in divine mausoleum that makes a pair with Primordial-Spirit-Initiating, Moon-Chasing Bow to really compete with the divine dragon.

Episode  32- yin yang jade was used to save Tianhe's life that was affected due to his mother being the host of Wangshu. Elder Zong Lian gave his manuscript used to forge the Xihe and Wangshu sword along with the secret of yin yang jade to Tianhe's father, that book is currently with Lingsha in her bag.

Episode 33- Red soul bead  in Lingsha's body through which Su Yao can absorb her power to become host of Wangshu sword herself by converting the red soul into Qiankun Soul. Soul stone bracelet worn by Lingsha in which she transferred her primordial spirit, the stones' light fade as and when the person's life span reduces.

Episode 34- Tianxiang life saving dew,  a magical medicine passed down from ancestors of Mengli's mother. This was given to Mengli by her mother. It can save a person's life at a critical time.

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Interesting facts, In the game the main character's journey takes them to below mentioned places and location, we have already seen a few of them in the drama so far... Fascinating to know they travel to so many places.

Locations
Qingluan Peak - Liu's Residence
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Settlements

Taiping Village - Shouyang City - Chenzhou City - Boxian Town - Qionghua Sect - Yueya Village - Wind Ravine - Jimo City - Land of Juchao - Ghost Realm - Fengdu City - Huanming Realm
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Dungeons

Shichen River Cave - Ziyun Mount - Chao Lake - Liu's Residence - Bagong Mountain - Nüluo Rock - Prince of Huainan Mausoleum - Qianfo Pagoda - Taiyi Mountain Trail - Trial Illusion - Yueya River Valley - Sword Forest - Bewitching Garden - Fox's Dwell - Shennong Cavern - Mount Buzhou - Abyss of Exile - God Investiture Platform - Huanming Realm - Qionghua Sect

 Anthony Tumiwa:

there are 4 elders of Qing Hua sect; Chong Guang, Qing Yang, Zong Lian, who is the 4th ? 

I am still on episode 5 but I think the 4th  elder would be 

Tai Qing [24th grandmaster of Qiong Hua Sect] from ep 1 (introduction).... 

If I come across new information in further episodes, I will amend the answer... 

 Anthony Tumiwa:

There are 8 sects in mount Kunxu, other than Qiong Hua sect, who else?

total of eight cultivation sects have existed within the Kunlun Mountains, named after the Eight Palaces of the Saint Realm, namely Kunlun (崑崙), Qionghua (瓊華), Biyu (碧玉), Zicui (紫翠), Langfeng (閬風), Tianyong (天墉), Xuanpu (懸圃) and Yuying (玉英). Out of the eight sects, only Kunlun Sect and Qionghua Sect, who focused on fusing magics into swordsmanship, have had any fame outside of the Kunlun Mountains.

(Info obtained from legend of sword and fairy wiki) 

 Anthony Tumiwa:

it is said that in Qionghua, the highest fighter is Xuan Xiao, which had already reached Taiqing realm lv.7.

could you find more information about Cultivation level?

Hey, I   am quite new to  Xianxia dramas, but because of the questions you ask, I may become an expert soon 😉

I am so far behind watching this drama, you are way ahead of me. So I found general information about cultivation in Xianxia rather than specific to this drama... Maybe if you ask these questions in general comment section, viewers who are watching the episodes as they release may be able to give better answers than me. 

But I am a curious person by nature so I like finding answers to things that I am unfamiliar with. 

Cultivation levels in Xianxia( general information, levels may change from author to author)

There are nine ranks of cultivation:
Qi Condensation, Foundation Establishment, Core Formation, Nascent Soul, Spirit Severing, Dao Seeking, True Immortal, Ancestral Immortal, Dao Immortal.

the Nine Phases of Qi Cultivation and Mastery — Discover, Gather, Circulate, Purify, Direct, Conserve, Store, Transform, and Dissolve. 

For more general information read from the links below:
https://xian-ni.fandom.com/wiki/Cultivation
https://xian-ni.fandom.com/wiki/Cultivation

Hope the information helps you. 

My apologies, my knowledge is limited.

i can only share the following..

Disciple Generation Surname

the first generation doesnt use this yet (the 4 Elders; Chong Guang, Qing Yang, Zong Lian, and Tai Qing)

but after that, start from the 2nd gen is:

2nd gen - Xuan (male disciple) - Su (female disciple)
3rd gen - Xu  (male) - Jing (female)
4th gen - Huai - Xuan (perhaps same pinyin, but different character)

note: Yun Tianqing refused to use it, but Tai Qing allowed him.

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There are 6 realms, i forgot what episode mentioned it, but in CP3,  cmiiw the main antagonist is too strong and nearly conquer all realms. The 6 realms are Human race, Ghost/Spirit, Beast, Immortal, Deity, and Demon.  Each races has sub-races/tribes, for example demon sub-race in CP5 is Yakhsa , in which their world sealed by goddess Nuwa, and their world was experiencing a drought, so they need to enter human world to survive.

And we also have item/weapon that can turn into shape (like ep1-2 of CP4, the talisman that Yun Tianqing left), which i dont know if it can be called race or not. And not forget semi-demon like protagonist of cp5.

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Mt. Shu Sect (aka Shushan) is the main sect in Chinese Paladin Universe, it's like Wudang and Shaolin in Jin Yong's or Tianshan sect in Liang Yusheng's.   Shushan sect mentioned or appeared in CP1,3,4,5 (dont know about 6 because i havent watched it yet).  in CP4, only one of its disciple showed up, senior Dao Zhen.  I think they introduce Qionghua sect as the main sect in CP4 to avoid boredom, but in CP5, they switch back to Shushan sect. 

--

One character, Li Xiaoyao, appeared in CP1,3,5. so i hope his name at least mentioned in CP4 and CP6, or flashback if possible. All Cp1,3,5 have descendant of Nuwa too.
Riding sword is a technique that All CP1,3,4,5 main lead need to learn. 

--

it has been a long time since i watched CP1,3,5 , so my memory is vague.
And the couples (the main couple and the secondary/thirdly) usually doesnt end up well  (exception the main couple of CP3, but with quotation mark).

--

Back to CP4, the members of Qionghua sect really make some confusions. there are so many of them, total of 4 generations. CMIIW :

1. Tai Qing = the 24th grandmaster of Qionghua
2. Chong Guang, elder
3. Qing Yang, elder
4. Zong Lian, elder, the 2nd master of Murong Ziying
5. Xuan Zhen, and Yun Tianqing = direct disciples of Tai Qing. Xuan Zhen is the 1st, Tianqing is the 2nd.
6. Xuan Zhen has 3 disicples = Xu Zhao, Xu Liang, Jing Ci
7. Xu Liang = historican recorder and energy/Qi faction leader
8. Xuan Ye = god daughter of Xu Liang
9. Xu Zhao = the black cloak, subordinate of ChongGuang, one of the faction leader (sword branch leader)
10. Su Yao = the 25th grandmaster 
11. Su Yu = mother of our hero, the owner of wangshu sword
12. Huai Xin = roommates of Yun Tianhe
13. Huai Xi = the bad guy, disciple of Xu Liang
14. Huai Shuo =  disicple of Xu Liang
15. Huai Shu - low rank disciple
16. Su Xi = one of the faction leader, who in charge of the library
17. Su Shen = good friend of Su Xi, the first master of Murong Ziying and Liu Mengli
18. Xuan Ji = Su Yao's God Daughter
19. Xuan Xiao = the strongest one, had reached Tai Qing realm lv.7
20. Xuan Yi = Su Yao's subordinate
21. Xu Yi = another faction leader, doesnt show up much
22. Ming Guang = another low level disciple, dont know why he keep his real surname by not using 'huai'
23. Huai Yan = disciple of Su Xi
24. Xuan zong = Qing Yang's disciple, deceased in war 19 years ago
25. Xuan xi = Qing Yang's disciple, deceased in war 19 years ago
26. Dao Yin = the 20th Grandmaster
27. Ming Chen = a gate keeper
28. and the last, our Ziying = same rank with Xu Generation, planned as the next grandmaster successor of Qionghua sect.

perhaps i miss some low-rank disciples.

and unknown role:

• Xuan Tian (the late Kathy Chow)
  
  

Hey, 

I am still so far behind in the series at episode 6...I have so much workload currently that I have just enough time to check the MDL site. I plan to binge watch all episodes soon in a few days, so at this point all the information that I have is either from first 6 episodes or the websites that I browsed to get some idea about these characters and the storyline. ( I have added the race, weapons and occupation of 4 main leads in my post above.) 

1.   As far as the age of the 4 main leads, I got them from softstar fandom wiki... Mengli would be 20 as mentioned because the series started 19 years ago and if SuYu and Yun Tianqing saved her 19 years ago when she was an infant of around 1 year then she would be around 20 years old.
If Tianhe was born after SuYu and Yun Tianqing defected from Qionghua Sect 19 years ago, he would be around 18 years.
For the other two characters Lingsha and Ziying we can believe softstar fandom wiki that they were 17  and 19 at the beginning of the series(about being called uncle, probably something to do with cultivation.In the beginning  episodes, If I remember correctly Lingsha was wondering loudly that Ziying was around the same age as Tianhe then why were the juniors of Qionghua sect  referring to him as uncle. Although the actor chosen to portray Ziying is & looks much older than the other cast members) 

2. Mengli's origin is really interesting, if you don't mind a little spoiler you can click the link below to see her race and ethnicity.
https://softstar.fandom.com/wiki/Liu_Mengli

3. 19 years ago if Suyu was the host of Wangshu sword and Xuan Xiao was the host of Yihe sword then they must have some emotional connection as far as my understanding of the swords' operation is concerned... Probably something went wrong in their relationship, either it was one sided attraction from Xuan Xiao's side or they broke off due to their different ideologies.

4.spoiler..... probable future storyline( don't read further if you don't want spoiler) 

I think it is after SuYu and Yun Tianqing saved Mengli(a monster baby) , they became disillusioned with the Qionghua sect that was using dark energy to advance in cultivation and waging constant war against the monster realm.

( Below Info is from a website) 

The Qionghua sect in particular gained fame during the Six Dynasties period, and sought to elevate the entire temple to a sacred place. However, their cultivation method involves infiltrating the Monster Realm to supply the energy of the twins Yihe (羲和劍) and Wangshuu (王舒劍), who can break through the force field shield. It involved stealing dark energy by kidnapping creatures and looting purple crystals. realm of saints. To this end, the Qionghua sect had two chosen disciples, a man and a woman, coexist with their respective swords, allowing the swords to absorb energy from their hosts. However, after the invasion of the Huangming clan's territory turned ugly and resulted in the Qionghua leader being killed by Queen Meng Mother Queen Qiyu in a bloody duel, many of the surviving members  felt disillusioned with their cause. And among them was Suyu, the organizer of Wangshu Sword, who abandoned the sect. As a result, Yihe Sword's host, Xuanxiao (Xuanxiao), loses control of his rampaging Qi and Gong, forcing the sect leader to seal him inside an ice cave. Nineteen years later, Xuanxiao broke the seal with the help of Su Yu's son, Yun Tianhe, and took control of the sect. He obtains the Wangshu Sword, re-enters the Monster Realm, and succeeds in gathering enough dark energy. He then activated his twin swords, causing Qionghua Temple to float towards the sky, attempting to force the entire sect to settle in the Saint's Realm. This abominable act not only caused the followers of even fewer moral sects to denounce and rebel against their cause, but also aroused the wrath of the gods. Nine Heavens Xuannu, the deity worshiped by the Qionghua sect, had her airborne temple destroyed in a fire in the sky. 

 Anthony Tumiwa:

in CP4, the demon realm is called Huanming, and divided into a few clans, one of them is sucking-dream clan, while in CP5, the demon realm is called You Min Tribe (Netherworld Tribe). I Think even though both are demon realms, but their world of realms are different?

Huanming demon realm members:

1. Chan You, 
2. Bei Ke, 
3. Wen Yao
4. Gui Xie
5. Ming Feng
6. Ji Can
7. Xi Zhong
8. Jing Chen
9. Feng Xie
10. "The Young Master"

For Sword and fairy 4

The Demon Realm (魔界), also known as the Lands of Nine Nether (九幽之地), is a dark, harsh and warring world where might makes right. Having access to only one of the Nine Springs, the demons fight in factions over territory and resources, and seven major tribes reign supreme, namely the Yaksha (夜叉), Rakshasa (羅剎), Asura (修羅), Garuda (迦樓羅), Gandharva (乾達婆), Dragonoids (龍眾) and Kinnara (緊那羅). Later on an eighth group named Heavenly Demons (天魔), consisting of deity rebels who exiled themselves out of Heaven, established themselves in the realm of the demons, completing the Eight Demonic Tribes (魔界八部眾).

The English translation for each major  demon tribe is from Sanskrit (Hinduism)... Huanming is direct translation from Chinese, I wonder what would be it's paraphrase or meaning?