5-1/2" x 3-1/2" (good condition; see scan for details)
 
The photographer who took the photo A'Sayyid Jawad Al Musawi is from the city of Karbala and he may have a photo studio (taken from the name behind the photo); as for these people in the photo, as per their clothes and their facial appearances, it seems there are from India, and they went to visit Karbala as part of a Shia-Muslim pilgrimage.