Thank you for submitting your item for appraisal. This appears to be an embossed bronze tondo in high relief depicting the fasting or hungry Buddha, protected by two nagas (?) and two matsya, the avatar of the hindu god vishnu. Which would suggest that Siddhartha Buddha is seen here as an incarnation of Vishnu. This appears to be a crossover representation of two religions, most likely manufactured in the Dhaka region in now Bangladesh. This area is known for the superb craftsmanship of brass or bronze items and the writing system which can be seen is most likely Bengali, the de facto national language of Bangladesh. Due to the embossing technique the characters are difficult to decipher and quite often those craftsmen simply copy or imitate inscriptions.
This is a very impressive and decorative relief and you are probably right regarding the age. Judging from the color this could be bronze ( heavier than brass alloy). No similar relief has been offered or sold recently. The estimate is based on brass or bronze items from that area of the same quality offered or sold at auction.