the eldest brother forever永远的大哥;永远的长兄
So The Eldest Daughter得之长女
the eldest branch长房
the eldest child最大的孩子
The Eldest Brother Said大王子说
Who was the eldest谁是老大
The eldest son大儿子;长子
the eldest brother大哥
We could consider that the king of the Donghu(east Hu)was the eldest son of the Huns' chan yu according to the meaning of Wuhuan tribe' s name and other cases.
乌桓部以“长子”为号和其他几个方面的情况看,可以认为东胡王就是匈奴单于的长子。
参考来源 - 乌桓演变考