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 "house" is a royal or noble family, not always ruling. Historians periodize the histories of many states and civilizations, such as Ireland (10th century), Roman Empire (27 BC – AD 1453), Imperial Iran (678 BC – AD 1979), 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 were traditionally reckoned patrilineally, such as those that followed 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.
