Geographically, Thailand is a diverse country. Thais generally divide it into four distinct regions. The Central region is largely delta country, dominated by the Chao Phraya River, and with rich soil. Southern Thailand is peninsula country, with the Andaman Sea on one side and the Gulf of Thailand on the other. The North is cool and mountainous. Northeastern Thailand is a vast plateau and flanked by the Mekong River. Each region has its own distinct ethnic peoples, speaking their own dialect, and practicing their own customs.