<Tr> <Td> <Table> <Tr> <Td> Goguryeo </Td> <Td> 37 BC--668 AD </Td> </Tr> <Tr> <Td> Baekje </Td> <Td> 18 BC--660 AD </Td> </Tr> <Tr> <Td> Silla </Td> <Td> 57 BC--935 AD </Td> </Tr> <Tr> <Td> Gaya confederacy </Td> <Td> 42--562 </Td> </Tr> </Table> </Td> </Tr> <Table> <Tr> <Td> Goguryeo </Td> <Td> 37 BC--668 AD </Td> </Tr> <Tr> <Td> Baekje </Td> <Td> 18 BC--660 AD </Td> </Tr> <Tr> <Td> Silla </Td> <Td> 57 BC--935 AD </Td> </Tr> <Tr> <Td> Gaya confederacy </Td> <Td> 42--562 </Td> </Tr> </Table> <Tr> <Td> Goguryeo </Td> <Td> 37 BC--668 AD </Td> </Tr> <Tr> <Td> Baekje </Td> <Td> 18 BC--660 AD </Td> </Tr>

How did north and south korea get its name