A basket of Buddhist scriptures had arrived…

Taizong issues an official declaration protecting the Nestorian church three years after Alopen’s arrival to Chang'an.

He erects China's first Christian church and recognizes twenty-one priests, likely all Persians, to administer it.

Tibetan forces, apparently commanded by Songtsän Gampo himself, raid the Tang frontier city of Songzhou (modern Songpan County in Sichuan) in the fall of 638, but meanwhile send emissaries to the Tang capital Chang'an, again offering tributes and declaring that they are intending to welcome a princess.

The size of Songtsän Gampo’s army is given as one hundred thousand by Tibetan sources and over two hundred thousand by Chinese sources.

They defeat a force sent against them by the Songzhou governor Han Wei.

According to the Chinese annals, Taizong respondd by commissioning the general Hou Junji to command an army, assisted by the generals Zhishi Sili, Niu Jinda and Liu Jian.

Led by Niu, the Tang army inflicts heavy casualties on the Tibetans in a surprise night attack.

Alarmed, Songtsän Gampo withdraws, sent emissaries and tributes to Chang'an to apologize and to again request marriage.

Emperor Taizong agrees this time.

However, no further action will be taken to carry out the marriage for about two years.

Roman emperors have endeavored to preserve uniform theological belief since their adoption of Christianity in the fourth century, and have persecuted those with differing Christological views, notably in Egypt, Syria, and Armenia.

Religious controversy has weakened the loyalties that Syrians and Egyptians render to Constantinople, and Heraclius seeks in 638 to placate Monophysite sentiment in these two provinces by promulgating the doctrine of Monothelitism, holding that Christ, although of two natures, had but one will, setting it forth as the official doctrine of the Eastern Orthodox Church.

Heraclius’ Ekthesis is vigorously opposed, notably by Maximus the Confessor, an influential unofficial political advisor and spiritual head in North Africa.

Neither in the East nor in the West will this compromise prove successful.

Heraclius’s son Heraklonas was probably born at Lazica while his father was on campaign against Khosrau II of the Sassanid Empire.

He was probably the fourth son of Martina and Heraclius, but the first one born free of physical deformity and eligible for the throne.

Heraklonas obtains through his mother’s influence the title of Augustus on July 4, 638.

Pyrrhus I becomes patriarch of Constantinople after the death of Sergius I.

He has been an advocate of Monothelitism and a close friend of Heraclius.

Islamic Arab forces under Abu Musa al-Asha'ari in the lower Zagros Mountains capture capture and destroy the flourishing Sassanian trade center of Susa in 638.

The Empire's field armies are withdrawn at some point in the mid-seventh century, probably in the late 630s, to Anatolia, the last major contiguous territory remaining to the Empire, and assigned to the districts that will become known as the themes.

Heraclius creates a buffer zone or no man's land in the heartland of Asia Minor.

In the mountainous terrain of Anatolia, the imperial forces develop a system of defensive guerrilla warfare.

The strategy is known as ‘shadowing warfare’, as it avoids battle with major Muslim invasions and instead attacks raiding parties on their return when they are laden with booty, captured livestock or prisoners.

Umar I dismisses Khalid ibn al-Walid after the conquest of Syria, owing to his ever-growing fame and influence.

He wants the Muslims to know that victory comes from God, not his general.

The invading Rashidun army under Khalid ibn al-Walid moves into eastern Anatolia, conquering without strong imperial resistance, capturing Malatya, which becomes a base for their raids further into Anatolia.

Arab forces march into Armenia, where they capture the cities Edessa and …

…Amida, up to the Ararat plain.

Acre comes under the rule of the Rashidun Caliphate beginning in 638, following the defeat of the imperial army of Heraclius by the Muslim army of Khalid ibn al-Walid in the Battle of Yarmouk, and the capitulation of the Christian city of Jerusalem to the Caliph Umar,

The actual conquest of Acre According to the early Muslim chronicler al-Baladhuri was led by Shurahbil ibn Hasana, one of the main field commanders during the Muslim conquest of Syria, and the city likely surrendered without resistance.