Cholas belonged to a minor chiefly family known as Muttaraiyar that held power in the Kaveri delta. They worked as subordinate to the Pallava kings of Kanchipuram. Vijayalaya, a member of the ancient chiefly family of the Cholas from Uraiyur, captured the delta from the Muttaraiyar in the middle of the ninth century. 'His town of Thanjavur and the temple for goddess Nishmbhasudini are some of his great creations. Vijayalaya's successors conquered neighboring regions and the kingdom grew in size and power. The Pandyan and the Pallava territories to the south and north were made part of this kingdom. Rajaraja I was the most powerful Chola ruler. He became king in 985 and expanded control over most of these areas. He was well known for the reorganization of the administration of his empire. His son Rajendra I continued his policies an even raided the Ganga valley, Sri Lanka and countries of Southeast Asia, developing a navy for these expeditions. The big temples of Thanjavur and Gangaikonda-Cholapuram built by them are architectural marvels.