The Buddhist calendar originated in India and varies among different geographic locations, as does the Hindu calendar, with which it shares many common elements. The method for determining the date of the new year is not uniform. among Buddhist sects. Theravada Buddhists (those primarily in Sri Lanka, Laos, Burma/Myanmar, Thailand, and Cambodia), using a Hindu calendar as their basis, calculate the months by the moon and the new year by the sun’s position in relation to the twelve segments of the heavens, each named for a sign of the zodiac. The solar new year begins when the sun enters Aries, usually between April 13th and 18th. The lunar months alternate between twenty-nine and thirty days in length. The first lunar month is usually sometime in December, except for the Burmese Buddhist calendar, which begins in April (see Hindu Calendar above for Burmese names). Periodically, the seventh month has an intercalary day, and an inter calary month is added every few years. Cambodia, Laos, and Thailand refer to the months by number. Tibetan Buddhists, whose calendar has been heavily influenced by the Chinese calendar, begin their new year at the full moon nearest to the midpoint of Aquarius. Mahayana Buddhists (those primarily in Tibet, Mongolia, China, Korea, and Japan) base their holidays on Buddhist, Chinese, or Gregorian calendars.