Princess Thoibi and her followers were fishing at the Loktak lake so the king told that no men should go near the lake where the princess was fishing.
Khamba too was aware of this as his sister Khamnu told min the situation.

As he slept, in his dream, Goddess Panthoibi came to him in the guise of Khamnu, and bade him get the vegetables together. Khamba woke up and wondered if he had indeed seen his sister or if it was a dream, but Gods put it into his mind that he had indeed seen his sister. So, he went down to the lake and got a boat there and rowed out, but in a wrong direction, so the God spread a veil of cloud over the hill leading him to the place where the Princess and her company were fishing
Theis illustration was my take of the episode of 'enn chingba' from the khamba Thoibi epic.