Cairn India, the 65% owned subsidiary of Cairn Energy, has started production from the largest of its 25 discoveries in the Barmer Basin in Block RJ-ON-90/1 in India.The first oil from the Mangala Field in Rajasthan Mangala was trucked to the Gujarat coast at the end of August.Oil production from the fields will increase over a period of two years to a peak production of 175,000 barrels of oil per day, at which point production from Rajasthan oil fields will account for over 20% of India's domestic oil production.‘This is a significant and historic event for both Rajasthan and India as the country's biggest onshore oil discovery for more than two decades is brought on production,’ claimed Rahul Dhir, managing director and chief executive of Cairn India.Cairn India is the operator of the Rajasthan block in which it holds a 70% participating interest with Oil and Natural Gas Corporation (ONGC), the Indian petroleum company.