Sayun

Seiyun
The Sultan Al Kathiri Palace, the most prominent landmark of Seiyun.
Seiyun Location in Yemen
Coordinates: 15°58′N 48°47′E / 15.967°N 48.783°E / 15.967; 48.783Coordinates: 15°58′N 48°47′E / 15.967°N 48.783°E / 15.967; 48.783
Country	Yemen
Governorate	Hadhramaut
Population (2006)
• Total	75 700
Time zone	Yemen Standard Time (UTC+3)

Say'un — (also transliterated as Saywun or Seiyun; Arabic: سيئون‎‎  Hadhrami pronunciation: [seːˈwuːn], Literary Arabic: [sæjˈʔuːn]) — is a city in the Hadhramaut region, in the Hadhramaut Governorate, of Yemen.

The most prominent landmark in the cityscape and surrounding plain is the tall and large Seiyun Palace of the Sultan of Kathiri, built in 1920s. As of 2006 the city's population was 75,700.

The town is served by Seiyun Airport.

Postage stamps from the former Sultanate of Kathiri (Aden-Kathiri), that was within the British Aden Protectorate (1869 - 1963), were sometimes inscribed "Kathiri State of Seiyun."