There was a sage named Atri. Atri performed very difficult tapasya. So difficult was the tapasya that Atri’s energy was thrown up into the sky. The sky could not bear this energy and hurled it down onto the earth. This energy then gave birth to Soma or Chandra, the moon god. Brahma took Chandra up into his chariot and drove the chariot around the earth twenty-one times. From whatever energy was left after Chandra has been created, the herbs were born.
Chandra also performed very difficult tapasya. One padma year consists of 10,000,000,000,000 normal years. For one hundred such padma years, Chandra mediated. After the meditation was over, Brahma appointed Chandra lord over seeds, herbs, brahmanas and the oceans. Chandra also performed a rajasuya yajna (royal sacrifice) as a celebration of his lordship. This gave him a lot pomp, glory, wealth and respect.
But all this merely served to turn Chandra’s head. The guru (teacher) of the gods was the sage Brihaspati. Brihaspati had a wife named Tara and Chandra abducted Tara. Despite the gods and the sages asking Chandra to return Tara, the moon god would not listen. A terrible war then raged over Tara, the gods fighting for Chandra. Shukracharya, the guru of the demons, fought on Chandra’s side and Shiva fought on Brihaspati’s side. This war (Samgram) came to be known as tarakamaya samgram, since it was fought over Tara.
Finally Brahma intervened and a truce was called. But Chandra and Tara had by then had a son, and Brihaspati refused to accept this son as his own. This son was Budha. As you already known, Budha married Ila and they had a son named Pururava.
The Brahma Purana now describes several kings belonging to the lunar dynasty.