The Platinum Map quest can be started in any zone.
You just need to farm Platinum and there is a chance to get [item=161088] item from every Platinum node.
I think that the best place to farm Platinum is Stormsong Valley
My regular path was like this: https://imgur.com/a/lv0AL0G
To complete this quest you need to find [npc=139792] in Vol'dun
/way Vol'dun 27.44 70.19 Ta'mil Nadu
He is south of the Terrace of the Devoted in small cave in the mountains.
The Platinum Map video: https://www.youtube.com/watch?v=1birOJOMbS4
All the BfA Horde Mining Zandalari Mining quests:
Id
Quest
Skill
Questgiver
Zone
Video
1
50
[npc=122694]
Zuldazar
https://youtu.be/XVNnN8jXEb8
2
130
[npc=122694]
Zuldazar
https://youtu.be/7LFQjnIFgng
3
50
[object=276619] Rank 2
[npc=122694]
Zuldazar
https://youtu.be/ZK4NRhu8peI
4
130
[object=276619] Rank 3
Exquisitely Crafted Brooch
Node Drop Item
https://youtu.be/EXI5gBbkLYw
5
50
[npc=122694]
World
https://youtu.be/gxaEgoTbI7s
6
135
[npc=122694]
World
https://youtu.be/Ld3lsLXSxGU
7
130
[object=276620] Rank 2
[npc=122694]
Zuldazar
https://youtu.be/1su0_dhfnjw
8
150
[object=276620]
[npc=122694]
Zuldazar
https://youtu.be/nm4zsqCd9ZU
9
150
[object=276620] Rank 3
[npc=139634]
Zuldazar
https://youtu.be/msQ-rY4iC-w
10
130
[item=161078]
Node Drop Item
https://youtu.be/_zk1oQ6H2m0
11
150
[item=161088]
Node Drop Item
https://youtu.be/1birOJOMbS4
12
150
[npc=139792]
Stormsong*
https://youtu.be/LkGCU1Q-vbc
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 items can drop from related herb in multiple zones. Farm the herb in any zone you want. I provide the recommended zone.
Alliance questchain is here: [spell=265852]