The original city of Ayuthaya was on an island where here rivers joined. Those rivers are the Lop Buri river, the Pra Sak river and the Chao Phraya river. This made the city very suitable for trade, even with other countries. The area was very fertile and suitable for growing crops. In addition, any invading enemy troops had great difficulty in invading the city. Also the land around the city could not always support an invader with food crops because of the flooding in the wet season.