So provide me a map before 1904 that had those islands. The problem is you Chinese can't provide something like that
Some of our maps:
1838 maps
Western map, Brion de la Tour, 1774
Text:
1776 book that described about our "Paracel Teams". Their misson was settling the sovereignty over Paracel, patrolling and exploiting in Paracel.
I have more than 100 old Western books which affirm Vietnamese sovereign over Paracels, pm me if you need some more evidences. It means that when the Westerners came, they saw that Vietnamese govs and people are administrating Paracels archipelago, not Chinese. Then they wrote what they saw.
So, wanna discuss about "history" side, Chinese?