For many, historical costume can be a challenge
Ancient Times - This covers Ancient Romans (Caesar etc.), Egyptians (eg. Cleopatra) and Greeks (eg. Aphrodite)
Medieval  The bit of English history between the arrival of William I (Battle of Hastings) through the Wars of the Roses (Richard III) to the early Henries 
Tudors  - The era of King Henry VIII and his wives, the glorious reign of Queen Elizabeth I and Drake and Raleigh
Georgians  also including the Regency period
Victorians - The era covering the middle to the end of the 19th century to 1900. Dickens characters etc.