Chaiyanam lies within the Nan Basin, which is part of the Chao Phraya Watershed.

Ban Bang Krathum is situated in the Nan Basin, which is part of the Chao Phraya Watershed.

Most drainage analyses, however, divide the Greater Nan Basin into the Nan Basin and the Yom Basin.

The next major wave of migration into the Nan Basin came not from the coast along the Chao Phraya, but rather from the mountainous areas of northern Thailand.

Even after this Thai migration, the population in the Nan Basin, other than along the banks of the Nan River and its major tributaries, was sparse.

Thap Yai Chiang lies within the Nan Basin, which is part of the Chao Phraya Watershed.

The city is situated in the Nan Basin, which is part of the Chao Phraya Watershed.

The land drained by the Wang Thong River is part of the Nan Basin and the Chao Phraya Watershed.

The province includes land within both of the Greater Nan Basin's sub-basins, i.e. the Nan Basin and Yom Basin.

The Thai brought rice-farming expertise to the mountainous areas of Northern Thailand, and eventually to the Nan Basin and the other lowland regions of Thailand.