Throughout history, the region between Krishna and Tungabhadra (Raichur Doab) remained a bone of contention between the major kingdoms of the south. Of the various empires that ruled the Deccan such as the Chalukyas, Mauryas, Bahamanis, Vijayanagara, Chola etc. Raichur has been part of them all.
There are three primary reasons for the fight over control of Raichur:
a. The fertility of the soil in the Raichur Doab due to the Krishna and Tungabhadra rivers made it a fertile rice producing resource. Therefore all kingdoms wanted to exploit the fertility of the area.
b. A number of important ports were situated in this region. Since trade with Ceylon, Indonesia, Malay peninusla etc. was quite substantial, the control over ports in the region would put the kingdom at a huge trade advantage.
c. The rich diamond mines in the region attracted the rulers of the major kingdoms. It is said that during the Vijayanagar Empire, the Raichur area provided a regular income to the kingdom from a steady diamond trade. Many historians are also of the view that the most celebrated diamonds like ‘Koh-i-noor’ and ‘the Nizam’ were sourced from the Krishna valley.
Source: History Discussion