(For map, see Indo-China.) The country may be best considered geographically in four parts: the northern, including the drainage area of the four rivers which unite near Pak-Nam Po to form the Menam Chao Phaya; the eastern, including the drainage area of the Nam Mun river and its tributaries; the central, including the drainage area of the Meklong, the Menam Chao Phaya and the Bang Pakong rivers; and the southern, including that part of the country which is situated in the Malay Peninsula.
In central Siam, after Bangkok and Ayuthia, places of importance on the Menam Chao Phaya are Pak-Nam at the river mouth, the seat of a governor, terminus of a railway and site of modern fortifications; Paklat, the seat of a governor, a town of Mohns, descendants of refugees from Pegu; Nontaburi, a few miles above Bangkok, the seat of a governor and possessing a large market; Pratoomtani, Angtong, Prom, Inburi, Chainat and Saraburi, all administrative centres; and Lopburi, the last capital before Ayuthia and the residence of kings during the Ayuthia period, a city of ruins now gradually reawakening as a centre of railway traffic. To the west of the Menam Chao Phaya lie Suphanburi and Ratburi, ancient cities, now government headquarters; Pechaburi (the Piply of early travellers), the terminus of the western railway; and Phrapatoom, with its huge pagoda on the site of the capital of Sri Wichaiya, a kingdom of 2000 years ago, and now a place of military, agricultural and other schools.
Its north-western shore is bordered by a dreary plateau, known as the Famine Steppe (Bek-pak-dala).
Farther south, towards Lake Balkash, on the southeastern frontier, is a wide waterless desert, Bek-pak-dala, or Famine Steppe.