Because the district has long history, and it appears the name of the city since the Ayutthaya period, so the name is thus understood to have district that has, however, by an assumed 3 implied.
Since it is a district with a long history. And the name of the city since the Ayutthaya period. The name of the district, it is assumed that there are, however. There were three presumed.
The district is with a long history. And appear city name since the Ayutthaya period. So the district name was assumed to have with what the 3 assumed it implies.