Ancient Skinning Knife

Ancient Skinning Knife quest can be started in Zuldazar from drop item [item=161431] that you can get from skinning mobs in any zone.
You need Rank 2 and some skill level. I was able to pick up the item after ~100 skill level

After you farmed the item, just bring the item back to [npc=122699] skinning trainer in Dazar'alor

Ancient Skinning Knife video: https://www.youtube.com/watch?v=9yYQBnnGRhs
All the BfA Horde Skinning Zandalari Skinning quests:

1

Lost But Not Forgotten

50-70

[spell=257147] Rank 2

[npc=122699]

Zuldazar

https://youtu.be/mtbEMitBv2w

2

Ancient Skinning Knife

100

[spell=257148] Rank 3

[item=161431]

Drop any zone

https://youtu.be/9yYQBnnGRhs

3

Hexoskeleton

100

[spell=257153] Rank 2

[npc=122699]

Zuldazar

https://youtu.be/aT8PitCZl80

4

Loa Fit For A King

150

[spell=257154] Rank 3

[npc=122699]

[zone=9028]

https://youtu.be/2pp5ja-cncg

5

Ceremonial Vestments

50-70

[spell=257150] Rank 2

[npc=122699]

Nazmir

https://youtu.be/01YCsdQ3E6Y

6

A Thicker Thread

150

[spell=257151] Rank 3

[npc=122699]

Vol'dun

https://youtu.be/Vp92KJbYkUk

Skill column is approximate level you need to have to get this quest. It can be lower, i provide here info of level i was able to pick up the quest.
Drop item can drop from skinning the related beast in any zone.

Alliance questchain info is here: [spell=265870]

Table with some good skinning farm spots under the spoiler.

Spoiler

Coarse Leather

Coordinates

NPC

Note

Video

Zuldazar

49.04 54.45

Gorillas

May be hard

https://youtu.be/vP6S9UM-jrw

Vol'dun

53.58 15.75

Hyenas

Good amount

https://youtu.be/ptIwrvi5P1I

Tiragarde Sound <- second best

58.47 47.27

Seals

Good amount

https://youtu.be/ZBWXyfxJLO8

Drustvar <- the best

66.01 42.29

Quillrats

Fast respawn

https://youtu.be/CEG4rwH21FU

Shimmerscale

Zuldazar <- second best

64.71 18.38

Serpents, eggs

Spawn from eggs

https://youtu.be/VLvWZAmODGI

Vol'dun

39.33 63.01

Saurolisks

Average

https://youtu.be/FP38FNI1Y90

Drustvar

65.42 39.85

Saurolisks

Fast respawn

https://youtu.be/Ms5pY5QAeNk

Tiragarde Sound

44.10 17.89

Saurolisks

Average

https://youtu.be/OBLlqti4L1k

Nazmir <- the best

64.51 66.02

Razorjaw

Huge amounts

https://youtu.be/YdND9jUiqZ0

/way Zuldazar 49.04 54.45 Gorilla Gorge Coarse Leather farm
/way Vol'dun 53.58 15.75 Bouldered Bluffs Coarse Leather farm
/way Tiragarde Sound 58.47 47.27 Umber Shore Coarse Leather farm
/way Drustvar 66.01 42.29 Hawthorne's Plot Coarse Leather farm
/way Zuldazar 64.71 18.38 Rootway Shimmerscale farm
/way Vol'dun 39.33 63.01 Whistlebloom Oasis Shimmerscale farm
/way Drustvar 65.42 39.85 Drustvar Shimmerscale farm
/way Tiragarde Sound 44.10 17.89 Westwind Weald Shimmerscale farm
/way Nazmir 64.51 66.02 The Shattered River Shimmerscale farm

This is the only Skinning rank that has an RNG aspect to it.

I received my [item=161431] about 35 skinning loots after completing the previous rank.
So either the RNG gods favored me or Blizzard learned from Legion that players hate 0.01% chance things.

Good Luck!

If you are like me and stuck at rank 2 of "Leather Skinning", make sure you travel to Nazjatar and train with Rolm. I was able to train actual dredged leather instead of having only leather skinning. This might seem silly to most, but I just switched to Skinning from Herbalism and couldn't figure out why I couldn't get this item to drop for me. Hopefully this comments helps someone! Have a great day!