Legolas's Age

[Imperica]

I know that. But I was merely underlining the fact that the Appendix says something else. In Unfinished Tales Oropher founded the Kingdom in Greenwood, while in the Appendix Thranduil is the first king of Mirkwood.

There is a large difference between Greenwood and Mirkwood. Greenwood is called Mirkwood after it is influenced by Sauron's presence in Dol Guldor.

So it is no mistake, Oropher did found the Kingdom of Greenwood. And Thranduil was the first king of Mirkwood.