Queen Seondeok of Silla builds, near Gyeongju, an astronomical observatory (Cheomseongdae) one of the oldest in East Asia.

The Muslims overthrow the rulers of Ghassan, which had remained a Roman vassal state.

Xuanzang sets out in 637 from Lumbini to …

…Kusinagara, the site of Buddha's death, before heading southwest to …

…the deer park at Sarnath, where Buddha gave his first sermon, and where Xuanzang finds fifteen hundred resident monks.

Traveling eastward, at first via Varanasi, …

…Xuanzang reaches Vaisali, …

…Pataliputra (Patna) and …

…Bodh Gaya.

He is then accompanied by local monks to …

…Nalanda, the great Buddhist university of Indian state of Bihar, where he will spend at least the next two years in the company of several thousand scholar-monks, whom he praises.

Xuanzang will study logic, grammar, Sanskrit, and the Yogacara school of Buddhism during his time at Nalanda.v