I think it's Indian and from the 1200-1500 time period. Looks to be in the 11 gram weight range too. Bounce it off some of these: http://images.google.com/images?hl=en&q=tanka coin&btnG=Google+Search&sa=N&tab=wi Bone
thanks all I can add something here the date on coin is 128 and something is writin above (king M Bahadur)...this info may help to identify ..
How about India (Hyderbad) Rupee dated AH128x. Listed in the Krause on page 644 as Y17. The coin appears VF which has a catalog of $7.