It is believed Xuanzang also visited Govishan (present day Kashipur) in the Harsha era, in 636, where he encountered one hundred monasteries of ten thousand monks (both Mahayana and non-Mahayana), Xuanzang is impressed by the king's patronage of both scholarship and Buddhism.

He spends time in the city studying early Buddhist scriptures, before setting off eastward again for …

…Ayodhya (Saketa), homeland of the Yogacara school.

Xuanzang now moves south to …

…Kausambi (Kosam), where he has a copy made from an important local image of the Buddha.

Xuanzang now returns northward to …

…Sravasti, …

…travels through Terai in the southern part of modern Nepal (here he finds deserted Buddhist monasteries) and thence to …

…Kapilavastu, his last stop before Lumbini, the birthplace of the Buddha.

Isidore of Seville, celebrated for his outstanding charity to the poor, dies on April 4, 636, leaving a compilation of scriptural, theological, and encyclopedic writings, including Etymologiae (“Origins”), a compendium of classical knowledge, and Historia de Regibus Gothorum, Vandalorum et Suevorum (“History of the Reigns of the Goths, Vandals, and Suebi”).

The instability of this period can be attributed to the power struggle between the kings and the nobility.

Religious unification has strengthened the political power of the church, which it exercises through church councils at Toledo along with the nobles.

The fourth council, held during the brief reign of Sisinand in 633, excommunicates and exiles the king, replacing him with Chintila.

The church councils are now the most powerful institution in the Visigothic state; they assume the role of regulating the process of succession to the kingship by election of the king by Gothic noble 'senators' and the church officials.

They also decide to meet on a regular basis to discuss ecclesiastical and political matters affecting the Church.

Chintila is elected by a convention of bishops and nobles in accordance with the 75th canon of the Fourth Council of Toledo as ruler of the Visigoths after the death of king Sisenand.

With his election, nothing changes and instability reigns.

In the Fifth Council of Toledo, convened in the church of St. Leocadia, the bishops accept in a decree that only Gothic nobility (with military functions) may be king of the Visigothic Kingdom.

Ariold has reestablished Arianism in the Lombard kingdom.

His only recorded wars are against the Avars, whom he had succeeded in repelling during an attempted invasion of northeast Italy.

Rothari (formerly duke of Brescia), marries Ariold’s widowed queen Gundeberga in 636, and succeeds him as king of the Lombards.

At the beginning of his reign, he puts to death many insubordinate nobles.

The Persians had decided to take back their lost territory as soon as Khalid had left Mesopotamia with half his army of nine thousand soldiers.

The Muslim army is forced to leave the conquered areas and concentrate on the border areas.

Umar immediately sends reinforcements to aid Misna ibn Haris in Mesopotamia under the command of Abu Ubaid al Saqafi.

The Persian forces had defeated by Ubaid in the Battle of Bridge, but, later Persian forces had been defeated by Misnah bin Harisah in the Battle of Baiyoub.

In 635, Yazdgerd III had sought alliance with Heraclius, who marries his daughter (according to traditions, his granddaughter) to Yazdegerd III, an old Roman tradition to show alliance.

While Heraclius prepares for a major offense in the Levant, Yazdegerd, meanwhile, orders the concentration of massive armies to pull back the Muslims from Mesopotamia for good.

The goal is well-coordinated attacks by both emperors, Heraclius in the Levant and Yazdegerd in Mesopotamia, to annihilate the power of their common enemy Caliph Umar.

Umar orders his army to retreat to the bordering areas of Mesopotamia near the Arabian desert and begins raising armies for another campaign into Mesopotamia.

The Arab armies are concentrated near Medina, and owing to the critical situation, Umar wishes to command the army in person.

This idea is opposed by the members of Majlis al Shura at Medina, who claim that the two-front war requires Umar's presence in Medina.

Umar appoints Saad ibn Abi Waqqas as commander for the campaign in Mesopotamia.

Saad leaves Medina with his army in May 636 and arrives at Qadisiyyah in June.

While Heraclius launched his offensive in May 636, Yazdegerd is unable to muster his armies in time to provide Constantinople’s forces with Persian support.

Umar, allegedly aware of this alliance, capitalizes on this failure: not wanting to risk a battle with two great powers simultaneously, he quickly moves to reinforce the Muslim army at Yarmouk to engage and defeat the imperial forces.

Meanwhile, Umar orders Saad to enter into peace negotiations with Yazdegerd III and invite him to Islam to prevent Persian forces from taking the field.