via Bangkok Post, 26 Sep 2019: Travel feature on the area just south of the city of Ayutthaya, where the foreign districts used to be located.
The ancient city of Ayutthaya was surrounded by rivers — the Lop Buri on the north side, the Pa Sak on the east side and the Chao Phraya on the remaining sides. South of the city island, known in Thai as Koh Muang, the Pa Sak merges with the Chao Phraya at the point where the latter makes a southward turn, away from Koh Muang.
Hundreds of years ago, from the confluence to the Takiayokhin Mosque near the mouth of Takhian canal, about 3.5km further downstream (see map), this section of the Chao Phraya was full of trading vessels from many parts of the world. And the areas on both sides of the river were home to foreigners, from the Chinese, the Malays and other Asians to Europeans of different languages and cultures.
Source: At the crossroads of history