Emperor Kōtoku makes a decree setting policy on the building of tombs.

He discontinues the old customs of sacrificing people in honor of a dead man, and forbids ill-considered rituals of purgation.

His Great Reform edict changes Japan's political order.

It will lead to the establishment of a centralized government with Kōtoku ruling from his palace, Naniwa Nagara-Toyosaki Palace, in Osaka.

Xuanzang completes his book Great Tang Records on the Western Regions, which will later become one of the primary sources for the study of medieval Central Asia and India.

Emperor Taizong destroys the Xueyantuo state during the campaign in the summer of 646 against them.

Slavic plunderers land near Siponto on the Adriatic in 646.

Aiulf personally leads his forces against the intruders, but his horse falls into a pit dug by the Slavs around their camp and he is surrounded and killed.

Radoald, who succeeds him with the support of King Rothari, knows the Slavic language and induces the invaders to depart.

Chindasuinth had cemented his control, somewhat famously, by preempting a revolt, executing at one time over two hundred Goths of the most noble families and five hundred more of the petty nobility; this in accompaniment with many banishments and confiscations of property.

All of this had occurred before any rebellion and without any investigation or trial or, for that matter, actual belief that a revolt was pending.

The Seventh Council of Toledo, held October 16, 646, consents to and backs his actions, toughening the punishments applied to those who rise against the sovereign and extending them even to members of the clergy who support them.

Gregory launches a rebellion against Constans in 646.

The obvious reason is the latter's support for Monotheletism, but it undoubtedly is also a reaction to the Muslim conquest of Egypt, and the threat it presents to imperial Africa.

The Arab chronicler al-Tabari on the other hand claims that Gregory's revolt was provoked by a levy of three hundred pounds of gold demanded by Constans.

Arab sources claim that after he was proclaimed emperor he minted coins with his own effigy, but none have so far been found.

It seems that both Maximus the Confessor and Pope Theodore I encouraged or at least supported Gregory in this venture.

The revolt seems to have found broad support among the populace as well, not only among the Romanized Africans, but also among the Berbers of the interior.

The Muslims retaliate by readying a large force of fifteen thousand, who promptly set out to retake Alexandria under command of the veteran Amr ibn Al-As.

The imperial troops, following their standard tactical doctrine, advance out of the city and seek an open battle away from the shelter of their fortifications near the fortified town of Nikiou.

Accounts of the battle portray the Muslim forces as relying heavily on their archers before eventually assaulting the imperial positions, driving many back and routing the rest in the process.

After this, the imperial forces are utterly defeated and withdraw from the region.

The defeat of Manuel's forces marks the last attempt by the Empire to recapture Egypt for some five hundred years, with only Emperor Manuel I Komnenos sending an expedition here in the twelfth century.

Amr ibn al-'As builds fortifications in Alexandria and quarters in the vicinity a strong garrison, which twice a year is to be relieved from Upper Egypt.

Taizong launches a second invasion of Goguryeo in 647 but, failing to subjugate the Korean kingdom, again withdraws.

Traveling Buddhist monks have brought sugar crystallization methods to China.

During the reign of Harsha (r. 606–647) in North India, Indian envoys in Tang China had taught sugarcane cultivation methods after Emperor Taizong of Tang (r. 626–649) had made known his interest in sugar, and China soon establishes its first sugarcane cultivation in the seventh century.

Chinese documents confirm at least two missions to India, initiated in 647 CE, for obtaining technology for sugar-refining.

Taizong establishes a Chinese military government to pacify the former territory of Xueyantuo, which extends to the Altai Mountains in the west.