Why did Rajaraja undertake a naval expedition against Ceylon (Sri Lanka) and Maldives?

The coasts of Kerala, Ceylon (Sri Lanka) and the Maldive Island had become rich through the Money that came to them from overseas trade. India sent textiles, spices and precious stones to the West Asian countries. The people who came from Western Asia to trade in these goods were the Arab merchants, who exchanged money for goods. Foreigners brought wealth to India through their trade. Rajaraja was aware of the importance of controlling the sea. He decided to show his strength along the coasts of South India. So, he took out a naval expedition and attacked both Sri Lanka and the Maldive Islands. He conquered the northern half of Sri Lanka.