Oropher

Yes, yes.

Thranduil and Oropher are Sindars from Doria.

So, yes, that is true.

But, again, even their...

That is, the language which we think of as Sindarin was still the language of the Noldor in Tolkien's head throughout the writing of The Lord of the Rings.

Like, that's still clearly true from reading the first drafts of the appendices, which were written after The Lord of the Rings was completed.

So... a lot is in flux but Bob the Sindar certainly did I get how so ever things might be shuffling around the Sindar clearly did exist in that the story of Thingol and Doriath are clearly there like what he did what he decided to do in the context like in the context in the later on in the appendices when he decides that Legolas and Thranduil and Oropher were in fact Sindar He...

He...

While he is indeed the son of Thranduil and therefore a prince of the woodland elves, he is also of Sindarin descent, and therefore a cousin of the Teleri.

His grandfather was Oropher of Doriath, one of the Sindarin survivors of the First Age.

This heritage puts Galadriel's earlier warning to Legolas in context.

Legolas Greenleaf, long under tree, in joy thou hast lived, beware of the sea.

From the two realms in exile came the Dunedain, tall and grim.

Down the Vale of Anduin the host gathered the sylvan elves of the Greenwood under Oropher, and of Lorien under Amdir.

And from the deep halls of Khazad-dûm came a host of Durin's folk, the dwarves marching to war beside elves and men.

To anyone standing on the slopes of the misty mountains as that column passed, it would have looked like a river of banners, so vast that the orcs of the mountains did not dare to harry it.

The clearest account of this comes not from the polished pages of the Silmarillion, but from Tolkien's later notes, gathered in Unfinished Tales, which means it carries a softer kind of canon, the author's intent rather than his finished word.

But it is among the most human details in the whole war.

The sylvan elves of the Greenwood and of Lorien marched under their own kings, Oropher and Amdia, and these two were, in Tolkien's words, unwilling to submit to the supreme command of Gil-galad.

They were of the older, cinder-in-nobility of the woodland realms.