Explanation:

All are Mahajanapadas. There were sixteen of such Mahajanapadas: Kasi, Kosala, Anga, Magadha,  Vajji, Malla, Chedi, Vatsa, Kuru, Panchala, Machcha, Surasena, Assaka, Avanti, Gandhara and  Kamboja.

Kasi is a region settled around Varanasi. It has a predominant position among the sixteen  Mahajanapadas. Matsya Purana and Alberuni talk immensely about Kasi read as Kausika and  Kaushika there. Also we come to know much about Kasi from the folklores of the Jatakas

Kosala comprises of Shravasti, Kushavati, Saket and Ayodhya. Also it constituted of the modern  cities of Oudh (Awadh), Uttar Pradesh. Ayodhya was under the control of the Kosala king Prosenjit. A neighboring state was the famous Magadha

Anga was one of the earliest of all. This was around the Gangetic plains. This state was known by  various names such as Malini, Champapuri, Kala malini, Champa malini etc. it was in the Atharva  Veda that the Angas were first mentioned

Magadha was a powerful kingdom and was run by Bimbisara and Ajatshatru, his son. As per the  Vedas Magadha is the 'semi Brahman' state. In the later Vedic scriptures and texts it was referred to  as Kikata. Also it is popular by various names as Magadhapura, Brihadrathapura, Vasumati etc.

Vajji comprised of many different social groups and villages. It was a confederation of many clans such as the Licchavis, the Vedehans, the Jnatrikas and most importantly the Vajjis. Its capital was  located at Vaishali

Malla has been mentioned in the Buddhist and the Jain works. It existed in a republic of nine  territories. The Mallas were known for their bravery and warlike temperament. They were conquered  by Magadha after Buddha's death

Chedi people existed on the southern part of the Yamuna River. The capital of Chedis was Suktimati  and the Rigveda gives details of this Mahajanapada. It was ruled by Sisupala and it was this city  where the Pandavas (from Mahabharata) chose to spend the thirteenth year of their exile.

Vatsa or also Vamsa followed a monarchial form of government. The capital of this Mahajanapada  was located at Kausambi. It became a hub of all the economical activities, business and trade

Kuru basically belonged to the Puru-Bharata family. These were the people who originated from  Kurukshetra. They are believed to have shifted to the republic form of government in the fifth of the  sixth century BCE.

Panchala was divided into two parts: Uttara Panchala and Dakhsina Panchala with Chhatravati and Kampilya there capitals respectively.

Machcha was located to the south of Kuru and west to the river of Yamuna. As per the Pali literature  the Machchas are generally linked with the Surasena. Its capital was Viratanagara

Surasena witnessed great metamorphism in religion. Its capital was Mathura. Earlier Lord Krishna  was worshipped here later the disciples of Buddha took over this Mahajanapada

Assaka also known as Ashmaka, this was situated in the southern part of the country. Its capital was  located at Potali.

Avanti lay in the western India. This kingdom nurtured Buddhism immensely. Its capital was known  as Ujjaini. Initially its capital was Mahissati which later was integrated into Ujjaini. Avanti later  dissolved in the Magadha Empire

Gandhara comprised of the Gandharas who were believed to be excellently tarind in the art of war  and have been mentioned in the Atharva Veda. The Gandhara are included in the Uttarapatha by the  Puranic and Buddhist traditions

Kamboja was believed to have consisted of the areas around the Hindukush. It is mentioned in the  great epic Mahabharata in many excerpts