The first coins of Siam were made during the reign of King Rama the 4th. At the time of his coronation, Pod Duang money was still in use. However, the manufacture of Pod Duang money by hand could not meet the increasing demand as new international trade agreements fueled the rapid expansion of trade and commerce in the region.
One of the first trade agreements Siam entered was the Bowling Agreement with England in 1855, which was soon followed by agreements with the United States, France, and Portugal. In 1857 Queen Victoria of England gave a small coining machine to King Rama the 4th. This led to the purchase of a larger, English steam - powered minting machine. The machinery was housed in the Sittikarn Mint, built by order of the King within the palace grounds in front of the royal treasury. The first flat coins of Siam, bearing an image of a crown on one side and the Chakra on the other, were produced in 1860.
These modern coins were used along with Pod Duang money in matching denominations of Chang, Tumlung, Baht, Salung, Fuang, and Pai. The reign of King Rama the 5th brought the use of copper coins with a portrait of the King on one side and a guardian deity of Siam called Phra Siam Devadhiraj on the other side. At this time, a nickel coin was produced as well with the King's portrait on one side and a three-headed elephant on the other.
This was the first reign ever to put a portrait of a Siamese King on coins. In 1898 the King replaced the old divisions of Thai currency with a system based on Baht and Satang, where 100 Satang it equal to 1 Baht. The Pod Duang money and cowry shell Hoy Bia were withdrawn from circulation once the quantity of minted coinage was sufficient to meet demand. This system of coinage is still in use today.