<Tr> <Th> Early period (330--717) </Th> </Tr> <Tr> <Td> <Ul> <Li> Constantinian - Valentinian era (Constantinian dynasty - Valentinian dynasty) </Li> <Li> Theodosian era </Li> <Li> Leonid era </Li> <Li> Justinian era </Li> <Li> Heraclian era </Li> <Li> Twenty Years' Anarchy </Li> </Ul> </Td> </Tr> <Ul> <Li> Constantinian - Valentinian era (Constantinian dynasty - Valentinian dynasty) </Li> <Li> Theodosian era </Li> <Li> Leonid era </Li> <Li> Justinian era </Li> <Li> Heraclian era </Li> <Li> Twenty Years' Anarchy </Li> </Ul> <Li> Constantinian - Valentinian era (Constantinian dynasty - Valentinian dynasty) </Li>

Who were four groups of invaders that threatened byzantine territory