Grey-cheeked Warbler 
(Phylloscopus poliogenys)

The grey-cheeked warbler (Phylloscopus poliogenys) is a species of leaf warbler (family Phylloscopidae).
The bird is native to Bangladesh, Bhutan, China, India, Laos, Myanmar, Nepal, Thailand, and Vietnam.

The name Phylloscopus combines the Ancient Greek phullon meaning "leaf" and skopos meaning "seeker" (from skopeo, "to watch").
poliogenys Greek polios grey; genus cheek.