The beginning of the empire is conventionally dated to the victory by its founder Babur over Ibrahim Lodi, the last ruler of the Delhi Sultanate, in the First Battle of Panipat (1526). During the reign of Humayun, the successor of Babur, the empire was briefly interrupted by the Sur Empire established by Sher Shah Suri, who re-established the Grand Trunk Road across the northern Indian subcontinent, initiated the rupee currency system and developed much of the foundations of the effective administration of Mughal rule. The "classic period" of the Mughal Empire began in 1556, with the ascension of Akbar to the throne. Some Rajput kingdoms continued to pose a significant threat to the Mughal dominance of northwestern India, but most of them were subdued by Akbar. All Mughal emperors were Muslims; Akbar, however, propounded a syncretic religion in the latter part of his life called Dīn-i Ilāhī, as recorded in historical books like "Ain-i-Akbari" and "Dabistān-i Mazāhib". The Mughal Empire did not try to intervene in native societies during most of its existence, rather co-opting and pacifying them through concilliatory administrative practices and a syncretic, inclusive ruling elite, leading to more systematic, centralized and uniform rule. Traditional and newly coherent social groups in northern and western India, such as the Marathas, the Rajputs, the Pashtuns, the Hindu Jats and the Sikhs, gained military and governing ambitions during Mughal rule which, through collaboration or adversity, gave them both recognition and military experience.