Satrughna halted at the Valmiki Asram enroute a battle with Lavana, the son of Madhu. At that same time twins Kusa and Lava were born. Valmiki named them Kusa and Lava after the grasses with which the children were purified.
Sri Rama’s nephews:
Sri Rama’s sons were Lava and Kusa. Lakshmana’s sons were Angada, Chandraketu, Bharata’s sons were Daksha ()(Takhsa) and Pushkara, Satrughna’s sons were Subaahu and Surasena. Quoted from The Mahabharata By Promatha Nath Mullick, Bharata obtained Kekaya from his maternal grandfather and his sons inherited it. They captured Gandhar as well. Their capitals were Takshasila and Pushkaravathi. It is said by some that the Asura Madhu whose son, Lavana was killed by Satrughna, was a Sattva-ta Yadava. Rama’s son Kusa founded Kusasthali which later became Dwaraka? Lakshmana’s sons ruled at Karapatha Desa with capitals as Angadiya and Candracaka, near the Himalayas.