Rajendra Chola, son of Rajaraja Chola was a great emperor, who conquered countries in South Asia. Cholas became a formidable Naval power during his reign.He had a Naval Academy established in Tamilnadu.He undertook an expedition to North India and reached upto Himalayas, thus earning the title Gangaikonda Chozhan, one who reached Ganga River. He brought Ganga Water and had an Abhishek performed for Siva in Thiruloki temple on the southern bank of River Kollidam.

During his campaign ,he conquered many kings in the North. I shall be writing one by one the kingdoms conquered by Rajendra Chola.

He conquered Pala kingdom located in what is now Bengal and Bangladesh.

The Medieval Chola king Rajendra Chola I led an expedition to North India between 1019 and 1024. The expedition traversed the states of Vengi, Kalinga, Odda and Bengal culminating with their arrival at the Ganges river. The Chola victory over the Pala king Mahipala I is considered to be the climax of the expedition. ..of the Chola Empire frequently invaded Bengal from 1021 to 1023 CE to get Ganges water and in the process, succeeded to humble the rulers, acquiring considerable booty. The rulers of Bengal who were defeated by Rajendra Chola were Dharmapal, Ranasur and Govindachandra, who might have been feudatories under Mahipala I of the Pala Dynasty.^[29] Rajendra Chola I also defeated Mahipala, and obtained from the Pala king “elephants of rare strength, women and treasure..

https://en.m.wikipedia.org/wiki/Pala_Empire#Revival_under_Mahipala_I

https://en.m.wikipedia.org/wiki/Chola_expedition_to_North_India#Sastri

The Pala Empire (r. 750-1162 CE) was an imperial power during the post-classical period in the Indian subcontinent, which originated in the region of  Bengal… Mahipala (or Mahipala I; r. 988–1038) was a notable king of the Pala dynasty, which ruled over much of the eastern regions of the Indian subcontinent between the 8th and 12th centuries. He was the son and successor of Vigrahapala II. Mahipala’s reign marked a resurgence in fortunes for the Pala empire, whose boundaries were expanded as far as Varanasi. However, his rule was temporarily hampered by the northern expedition of the Chola king, Rajendra I. https://en.m.wikipedia.org/wiki/Mahipala