Eurasian Curlew

Beautiful!

Thanks @LennyWorthington

Thanks for you comment!! I guess is the arquata specie because, as you said, the back was white.

There are two species of Curlew in Thailand.
Of which this is one.
From what I can see in the flight shots these birds seem to be showing a white back and rump which would make them Eurasian Curlew Numenius arquata.
But.The bills look very long which would make them Eastern Curlew Numensis madagascariensis.Maybe you can remember how much white on the back and rump you saw.The back and upertail of madagascariensis is washed rufous.
Whereas the back and uprtail of arquata is white.I hope that is clear.