Editing 638 (section)

== Events ==
<onlyinclude>

=== By place ===
==== Byzantine Empire ====
* Emperor [[Heraclius]] creates a [[buffer zone]] (or [[no man's land]]) in the heartland of [[Asia Minor]]. In the mountainous terrain of [[Anatolia]], the Byzantine forces develop a system of defensive [[guerrilla warfare]]. The strategy is known as ‘shadowing warfare’, as it avoids battle with major [[Muslim]] invaders, and instead attacks [[Raid (military)|raiding]] parties on their return when they are laden with [[Looting|booty]], captured [[livestock]] or prisoners.{{sfn|Nicolle|2009|p=52}}
* [[July 4]] &ndash; [[Heraklonas]], age 12, son of Heraclius, obtains (through the influence of his mother [[Martina (empress)|Martina]]) the title of ''[[Augustus (honorific)|Augustus]]''. This brings him in rivalry with his elder half-brother [[Constantine III (Byzantine emperor)|Constantine]].   
* Heraclius issues his ''[[Ecthesis|Ekthesis]]'', espousing the Monothelete doctrine (that there is only one will in [[Christ]]), and setting it forth as the official [[doctrine]] of the [[Eastern Orthodox Church]]. The ''Ekthesis'' is vigorously opposed, notably by [[Maximus the Confessor]].

==== Britain ====
* King [[Oswald of Northumbria|Oswald]] and his Northumbrian army [[Siege|besiege]] and conquer [[Edinburgh]] ([[Scotland]]). His half-brother, [[Oswiu of Northumbria|Oswiu of Bernicia]], marries Princess Rhiainfelt, heiress of [[Rheged|North Rheged]] ("Old North"). [[Northumbria]] embraces North Rheged in a peaceful takeover, and Oswiu becomes a sub-king (approximate date).

==== Arabian Empire ====
* [[January]] &ndash; The [[Plague of Amwas]] breaks out.
* Autumn &ndash; The [[Saudi Arabia|Arabian]] forces under [[Abu Ubaidah ibn al-Jarrah]] storm [[Caesarea Maritima]], capital of [[Palestine (region)|Byzantine Palestine]], and effect their final capture of [[Ascalon]] (modern [[Israel]]). Caliph [[Umar|Umar I]] stops the [[Rashidun Caliphate#Occupation of Anatolia|Muslim invasion]], and appoints Abu Ubaidah [[governor]] of [[Syria]].
* [[Arab–Byzantine wars#Arab conquest of Roman Syria: 634–638|Arab-Byzantine War]]: The invading [[Rashidun army]] under [[Khalid ibn al-Walid]] moves into Anatolia, conquering (without strong Byzantine resistance) the cities of [[Kahramanmaraş]], [[Kayseri|Caesarea Cappadociae]], [[Sivas|Sebastia]], and [[Malatya]] (west of the [[Taurus Mountains]]). Arab forces march into [[Byzantine Armenia|Armenia]], where they capture the cities [[Edessa]] and [[Amida (Mesopotamia)|Amida]] up to the [[Ararat plain]]. 
* Umar I dismisses Khalid ibn al-Walid after the [[Muslim conquest of the Levant|conquest of Syria]], owing to his ever-growing fame and influence. He wants the Muslims to know that victory comes from [[Allah|God]], not his general.   
* [[Abu Musa Ashaari|Abu Musa al-Asha'ari]], companion (''[[sahabah]]'') of [[Muhammad]], establishes [[Hafar al-Batin]], located in the northeastern region of the [[Arabian Peninsula]]. He orders the digging for new [[Water well|well]]s, along this desert route that Muslims travel from [[Iraq]] to [[Mecca]] for the ''[[Hajj]]'' (pilgrimage).

==== Asia ====
* The [[Tibetan Empire]], seeking an [[Marriage of state|alliance through marriage]] with [[Tang dynasty]] China, launches an [[Tibetan attack on Songzhou|attack on Songzhou]] that is repelled by Chinese forces, but is followed by the marriage of the Chinese [[Princess Wencheng]] to Tibetan ruler [[Songtsän Gampo]].

=== By topic ===
==== Arts and sciences ====
* The [[Islamic calendar]] is introduced by Abu Musa al-Asha'ari. He convinces Umar I to make notes of an era for Muslims. 
* [[March 22]] &ndash; Year 0 of the [[Burmese calendar]], based on the [[Buddhist calendar|Chula Sakarat]], is also used in the [[Indochina|mainland of Southeast Asia]].

==== Religion ====
* [[October 12]] &ndash; [[Pope Honorius I]] dies at [[Rome]] after a 13-year reign, and is succeeded by [[Pope Severinus|Severinus]], but the Byzantine emperor Heraclius will delay the new pope's [[consecration]] until May [[640]]. 
* [[December 20]] &ndash; [[Patriarch Pyrrhus of Constantinople|Pyrrhus I]] becomes [[Ecumenical Patriarch of Constantinople|patriarch of Constantinople]], after the death of [[Sergius I of Constantinople|Sergius I]]. He has been an advocate of [[Monothelitism]] and a close friend of Heraclius.</onlyinclude>