The books frequently mention ¹ the sixteen great countries (Mahājanapada) that existed in the time of the Buddha. They are:
The Jaina Bhagavatī sutta gives a slightly different list: Aṅga, Baṅga, Magadha, Malaya, Mālava, Accha, Vaccha, Kocchaka, Pādha, Lādha, Bajji, Moli, Kāsi, Kosala, Avaha and Sambhuttara (PHAI. p.60).
¹ e.g., A.i.213; iv. 252, 256, 260; a list of twelve is found at D.ii.200, in which the last four are omitted. The Niddesa adds the Kaliṅgas to the sixteen and substitutes Yonā for the Gandhāra (CNid., p.37).