17 Hijri

17 Hijri (abbreviated 17 H) is the seventeenth year of the Hijri calendar, the lunar calendar that begins from the Prophet Muhammad's migration from Mecca to Medina. This year corresponds roughly to 638 CE, though the correspondence is not exact because the Hijri year is about 11 days shorter than the solar year.

During this period, the caliph was Umar ibn al-Khattab, the second of the Rightly Guided Caliphs. The year falls within a time when the Muslim administration, based in Medina, was extending control over the lands of the Levant and Iraq, and establishing new administrative structures to govern these newly conquered territories.

The Hijri Calendar

Historical tradition generally holds that the decision to adopt the Hijri calendar—counting years from the migration—was made during Umar's time, around 17 H. The stated reason was administrative necessity: official documents and decrees required a clear, unambiguous dating system. The month of Muharram was chosen as the beginning of the year.

Territorial Expansion

The years 15–17 H saw the conquest of parts of the Levant and Iraq. The capture of Bayt al-Maqdis (Jerusalem)—attributed by some sources to Umar's visit to the region and a reported peace agreement—is dated by some authorities to 16 H and by others to 17 H. The founding of military garrison cities such as Kufa and Basra, which later became major urban centers, is also placed within this period.

Internal Administration

During this time, new administrative institutions were established, including the divan (register) for recording military pay distribution and the system for collecting land tax in newly conquered territories. Provincial governors were appointed over the Levant, Iraq, and Egypt, answerable directly to the caliph in Medina.

Chronological Correlation

When converted to the Common Era, 17 H falls between the autumn of 637 and the end of 638 CE. Because the Hijri calendar is based solely on the lunar cycle, each year begins roughly 11 days earlier than in the Gregorian calendar, which means the start of each Hijri year shifts through the seasons.