 In addition, it is commonly thought that Old Chinese had syllables ending in clusters , , and (sometimes called the "long entering tone" while syllables ending in , and are the "short entering tone").Clusters later were reduced to /s/, which, in turn, became and ultimately tone 3 in Middle Chinese (the "departing tone").The first Chinese philologists began to describe the phonology of Chinese during the Early Middle Chinese period (specifically, during the Northern and Southern Dynasties, between 400 and 600 AD), under the influence of Buddhism and the Sanskrit language that arrived along with it.