Step 1: Recall the count: Buddhist and Jaina texts (like the Anguttara Nikaya) list sixteen major territorial states that had emerged in northern India by the 6th century BCE.
Step 2: Name a few examples: These 'Solah (16) Mahajanapadas' included Magadha, Kosala, Vatsa, and Avanti among others, some monarchies and some ganasanghas (oligarchic republics).
Final Answer: 16 (sixteen) Mahajanapadas.