16 events the sources record for this year, grouped by region.
What happened
China (2)
The king built a wall of more than a thousand li from the Buyeo fortress in the northeast to the sea in the southwest; it was completed in sixteen years. (Samguk Sagi (History of the Three Kingdoms) 卷20 榮留王 14年)
In August 631 (Jiachen day), an envoy is sent to Goguryeo to gather and bury the bones of those who fell in battle in the Sui era, and to hold memorial sacrifices. (Zizhi Tongjian (Comprehensive Mirror) 권193 631년 항)
Central Asia (1)
About one hundred li to the southeast, crossing a great mountain ridge and a wide river, he reached Na-kie-lo-ho (Nagarahara); 600 li from east to west, 250 to 260 li from north to south. (Xuanzang, Great Tang Records on the Western Regions Si-yu-ki (Beal 1884) vol.1 Bk II Nagarahara)
South Asia (12)
Some six hundred li east, passing mountains and valleys, skirting the Black Mountains and crossing the frontier of North India, he reached the country of Lan-po (Lamghan). (Xuanzang, Great Tang Records on the Western Regions Si-yu-ki (Beal 1884) vol.1 Bk II Lamghan)
About five hundred li to the southeast, across mountains and valleys, he reached the kingdom of Gandhara (Purushapura); about 1,000 li from east to west and 800 li from north to south (numeral unclear in the OCR). (Xuanzang, Great Tang Records on the Western Regions Si-yu-ki (Beal 1884) vol.1 Bk II Gandhara (Purushapura))
About fifty li northeast of the monastery of King Kaniṣka, crossing a great river, he reached the city of Pu-shi-kie-lo-fa-ti (Pushkalavati); its circumference is 14 to 15 li, and it is very populous. (Xuanzang, Great Tang Records on the Western Regions Si-yu-ki (Beal 1884) vol.1 Bk II Pushkalavati)
Going north from U-to-kia-han-ch'a (Udakhanda), over mountains and across a river, about six hundred li, he reached the kingdom of Udyana. (Xuanzang, Great Tang Records on the Western Regions Si-yu-ki (Beal 1884) vol.1 Bk III Udyana)
The kings of Udyana mostly made Mungali their capital; its circumference is 16 to 17 li, and its population is dense. (Xuanzang, Great Tang Records on the Western Regions Si-yu-ki (Beal 1884) vol.1 Bk III Mungali)
Crossing a plank road and going on some five hundred li, he reached the country of Po-lu-lo (Bolor); its circumference is about four thousand li, in the middle of the great snowy mountains. (Xuanzang, Great Tang Records on the Western Regions Si-yu-ki (Beal 1884) vol.1 Bk III Bolor)
After crossing a river he reached the kingdom of Takshasila; its circumference is about two thousand li and the capital's about ten li; the royal line had ended and the nobles were contending. (Xuanzang, Great Tang Records on the Western Regions Si-yu-ki (Beal 1884) vol.1 Bk III Taxila)
Going southeast over mountains and valleys seven hundred li, he reached the kingdom of Simhapura; its circumference is 3,500 to 3,600 li, and its west borders the Indus River. (Xuanzang, Great Tang Records on the Western Regions Si-yu-ki (Beal 1884) vol.1 Bk III Simhapura)
Following the mountains southeast about five hundred li, he reached the country of Uras'a (Urasa); its circumference is about two thousand li. (Xuanzang, Great Tang Records on the Western Regions Si-yu-ki (Beal 1884) vol.1 Bk III Urasa)
After going more than one thousand li southeast from Urasa, passing mountains, cliffs and iron-chain bridges, he reached Kashmir. (Xuanzang, Great Tang Records on the Western Regions Si-yu-ki (Beal 1884) vol.1 Bk III Kashmir)