Srimad Bhagavatham - Story of Mandhata
King Yuvanaswa was born in Ikswaku lineage. Being issueless, he retired to the forest along with his 100 wives. The sages of that hermitage took pity on him and conducted a sacrifice intended to propitiate Indra.
The king Yuvanaswa felt thirsty at midnight and entered the sacrificial hut. Not knowing it as divine water consecrated with the mantra, he drank and went back.
The next morning, seeing the sacrificial pitcher empty, the priest enquired and found the king consumed the divine water that had a capacity to produce a male child.
The priest remained hapless and left it to the play of destiny. The king at last gave birth to a male child splitting open his right pelvis.
When the baby cried out of hunger, the brahmanas were perplexed as to who would give milk to the baby.
Indra put his index finger dripped with nectar into the baby's mouth saying “ suck me (Mam Dhata). Do not cry”. Hence, he was named Mandhata.
King Yuvanaswa survived by the grace of Brahmanas and attained perfection through asceticism.
The powerful Emperor Mandhata ruled the entire globe. The whole extent of land from the point where the sun rises to the point where it sets is called the territory of Mandhata.
The Emperor had three sons, viz., Purukutsa, Ambarisa and Muchukunda, and 50 daughters. All the fifty daughters choose Sage Saubhari as their husband.
Ambarisa was adopted by his grandfather, Yuvanaswa, and a son, Yauvanaswa, was born to Ambarisha.
Purukutsa was married to Narmada and was taken to Rasatala to protect against Gandarvas, who were enemies of Nagas. Satyavrata (famously called Trishanku) is a descendent of Purukutsa.
Source: Bhagavatha Mahapurana
Please note Ambarisha, son of Naabhaga and a great devotee of Srihari, is different from Ambarisha, son of Mandata.