Kosala Proper or Uttara Kosala is the kingdom of the celebrated personality of Treta Yuga, Raghava Rama.

Ayodhya is its capital, presently in Faizabad district, Uttar Pradesh.

Rama's sons Lava and Kusha inherit parts of this kingdom.

Lava rules from the city called Sravasti and Kusa from the city called Kushavati.

A colony of Kosala kings exists in Madhya Pradesh.

It is called Dakshina Kosala.

Rama's mother Kausalya is from this kingdom.

King Rama extends his influence up to the island-kingdom of Lanka situated in the southern ocean.

He has friendly relations with the southern kingdom of forest dwellers (Vanaras) called Kishkindha.Rama's brother Bharata colonizes the Gandhara kingdom and founds the city of Takshasila there.

Gandhara lies close to Kekeya Kingdom, the native kingdom of Bharata's mother, Kaikeyi.

Rama's second brother Lakshmana founds the city of Lakshmanapura near the river Ganges which is now known as Lucknow.

He colonizes the Vanga kingdom and founds the city of Chandrakanta there.

Rama's youngest brother Satrughna destroys the forest called Madhu and founds the city of Mathura which later becomes the capital of the Surasena Kingdom.Nishadha king Nala's friend Rituparna is a ruler of Kosala.

Brihadbala, another ruler of Kosala during Dwapara Yuga, takes part in the Mahabharata war and is killed by Abhimanyu, the son of Arjuna.