<Ul> <Li> Kholop </Li> <Li> Panyarring </Li> <Li> Thrall </Li> <Li> Serfs <Ul> <Li> History </Li> <Li> Russia </Li> </Ul> </Li> <Li> Slave market </Li> <Li> Slave raiding </Li> <Li> Child soldiers </Li> </Ul> <Li> Serfs <Ul> <Li> History </Li> <Li> Russia </Li> </Ul> </Li> <Ul> <Li> History </Li> <Li> Russia </Li> </Ul> <Dl> <Dt> Naval </Dt> </Dl>

What are the three countries in the triangular trade