Kosala (IPA: [koːɕɐlɐ]), sometimes referred to as Uttara Kosala (lit. 'Northern Kosala') was one of the Mahajanapadas of ancient India. It emerged as a small state during the Late Vedic period and became (along with Magadha) one of the earliest states to transition from a lineage-based society to a monarchy. By the 6th century BCE, it had consolidated into one of the four great powers of ancient northern India, along with Magadha, Vatsa, and Avanti.
Kosala belonged to the Northern Black Polished Ware culture (c. 700–300 BCE) and was culturally distinct from the Painted Grey Ware culture of the neighboring Kuru-Panchala region, following independent development toward urbanisation and the use of iron. The presence of the lineage of Ikshvaku—described as a raja in the Ṛgveda and an ancient hero in the Atharvaveda—to which Rama, Mahavira, and the Buddha are all thought to have belonged—characterized the Kosalan realm.