A dynasty is a sequence of rulers from the same family, usually in the context of a monarchical system, but sometimes also appearing in republics. A dynasty may also be referred to as a "house", "family" or "clan", among others. The longest surviving dynasty in the world is the Imperial House of Japan, otherwise known as the Yamato dynasty, whose reign is traditionally dated to 660 BC and historically attested from AD 781.
Historians periodize the histories of many states and civilizations, such as Ancient Iran (3200 - 539 BC), Ancient Egypt (3100 – 30 BC) and Ancient and Imperial China (2070 BC – AD 1912), using a framework of successive dynasties. As such, the term "dynasty" may be used to delimit the era during which a family reigned.
Before the 18th century, most dynasties throughout the world have traditionally been reckoned patrilineally, such as those that follow the Frankish Salic law. In polities where it was permitted, succession through a daughter usually established a new dynasty in her husband's family name. This has changed in all of Europe's remaining monarchies, where succession law and conventions have maintained dynastic names de jure through a female.