sentences:  The current system of the Javanese calendar was inaugurated by Sultan Agung of Mataram in the Gregorian year 1633 AD.Prior to this, the Javanese had used the Hindu calendar (Saka), which begins in 78 CE and uses the solar cycle for calculating time.Sultan Agung's calendar retained the Saka calendar year system of counting, but differs by using the same lunar year measurement system as the Islamic calendar, rather than the solar year.