During the 9th century several important developments took place. First, there was a major effort by the Church to unify the many chant traditions, and suppress many of them in favor of the Gregorian liturgy. Second, the earliest polyphonic music was sung, a form of parallel singing known as organum. Third, and of greatest significance for music history, notation was reinvented after a lapse of about five hundred years, though it would be several more centuries before a system of pitch and rhythm notation evolved having the precision and flexibility that modern musicians take for granted.