Hyderabad is the largest city in the South Indian state of Telangana. Currently, Hyderabad is the common capital of Telangana and Andhra Pradesh states, an arrangement that is scheduled to last for a maximum of ten years. Occupying 650 square kilometres , along the banks of the Musi River, it has a population of about 6.8 million and a metropolitan population of about 7.75 million, making it the fourth most populous city and sixth most populous urban agglomeration in India. At an average altitude of 542 metres, much of Hyderabad is situated on hilly terrain around artificial lakes, including Hussain Sagar—predating the city's founding—north of the city centre.Established in 1591 by Muhammad Quli Qutb Shah, Hyderabad remained under the rule of the Qutb Shahi dynasty for nearly a century before the Mughals captured the region. In 1724, Mughal viceroy Asif Jah I declared his sovereignty and created his own dynasty, also known as the Nizams of Hyderabad. The Hyderabad State ultimately became a princely state during British rule, and remained so for 150 years, with the city serving as its capital. The city continued as capital of a new Hyderabad State after the Nizam acceded to the Indian Union in 1948. In 1956, it became the capital of Andhra Pradesh, formed by merging Telangana region of Hyderabad State with the Telugu-speaking Andhra State. In June 2014, after Telangana state was carved out of Andhra Pradesh, Hyderabad became part of Telangana state and the joint capital of both states.