A castellany was a district

District

Districts are a type of administrative division, in some countries managed by a local government. They vary greatly in size, spanning entire regions or counties, several municipalities, or subdivisions of municipalities.-Austria:...

 administered by a castellan

Castellan

A castellan was the governor or captain of a castle. The word stems from the Latin Castellanus, derived from castellum "castle". Also known as a constable.-Duties:...

.

Castellanies appeared during the Middle Ages

Middle Ages

The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...

 and in most current states

Sovereign state

A sovereign state, or simply, state, is a state with a defined territory on which it exercises internal and external sovereignty, a permanent population, a government, and the capacity to enter into relations with other sovereign states. It is also normally understood to be a state which is neither...

 are now replaced by a more modern type of country subdivision.

The word is derived from castle

Castle

A castle is a type of fortified structure built in Europe and the Middle East during the Middle Ages by European nobility. Scholars debate the scope of the word castle, but usually consider it to be the private fortified residence of a lord or noble...

 and literally means the extent of land

Real property

In English Common Law, real property, real estate, realty, or immovable property is any subset of land that has been legally defined and the improvements to it made by human efforts: any buildings, machinery, wells, dams, ponds, mines, canals, roads, various property rights, and so forth...

 and jurisdiction

Jurisdiction

Jurisdiction is the practical authority granted to a formally constituted legal body or to a political leader to deal with and make pronouncements on legal matters and, by implication, to administer justice within a defined area of responsibility...

 belonging to a given castle.

It also renders equivalent, often cognate, terms in other languages. Examples of French châtelainies include the castellanies of Ivry-la-Bataille

Ivry-la-Bataille

Ivry-la-Bataille is a commune in the Eure Department in the Haute-Normandie region in northern France. Ivry-la-Bataille was formerly known as Ivry.-History:The Battle of Ivry took place near Ivry on 14 March 1590...

, Nonancourt

Nonancourt

Nonancourt is a commune in the Eure department in Haute-Normandie in northern France.-Population:-References:*...

, Pacy, Vernon

Vernon, Eure

Vernon is a commune in the department of Eure in the Haute-Normandie region in northern France.It lies on the banks of the Seine River, about midway between Paris and Rouen...

 and Gaillon

Gaillon

Gaillon is a commune in the Eure department in northern France.-History:The origins of Gaillon are not really known. In 892, Rollo, a Viking chief, might have ravaged Gaillon and the region, before he became the first prince of the Normans and count of Rouen in 911.The Gaillon history did begin,...

, all in Normandy, which under in the treaty of Issoudun (1195, after a war with king Richard of England) were acquired for the French crown by Philip Augustus.
Examples from Poland include Lenczyc and Sieradz

Sieradz

Sieradz is a town on the Warta river in central Poland with 44,326 inhabitants . It is situated in the Łódź Voivodship , but was previously the eponymous capital of the Sieradz Voivodship , and historically one of the minor duchies in Greater Poland.It is one of the oldest towns in Poland,...

 (both once a duchy), Rozpoza, Spicimir and Wolborg (in Cracow diocese) and Ottmachau in Silesia.