From the pages of history

Situated on one of India's oldest pilgrimage routes from Mahakaal at Ujjain on river Kshipra, to Omkareshwar on the river Narmada and onwards to Rameshwaram, Indore was a convinient resting place.

It was on the route of the Marathas of Deccan on their way to North India. These Maratha guerilla warriors were in constant battle with the Mughal empire. Their army transit camps here attracted the local Zamindars (landlords) who, drawn by the promise of lucrative trade, settled in the villages on the confluence of the Khan and Saraswati rivers, thereby laying the foundation of this commerce centre in 1715. In 1741, temple of Indreshwar was erected in the town, from which it derives the name Indore.

The trade centre grew rapidly under the Holkar dynasty (1733-1818). The remains of their two century old palace still stand in the main square (called Rajwada). The city became the capital of the Indore princely state in 1818 after the British forces under Sir John Malcolm defeated the Holkars led by Rani Krishnabai Holkar at Mahidpur. She signed the treaty of Mandsaur by which the control of Indore went in the hand of the East India Company. Between 1948 and 1956, Indore served as the summer capital of the former Madhya Bharat state. Currently, it is the commercial capital of M.P. 

Source: Grolier Multimedia Encyclopedia and Encyclopedia Britannica