Under Goguryeo , the dynasty 's territory extended southward into Korean peninsula .
Dongducheon became part of the kingdom in the form of naeulmae hyun ( a certain form of ancient village land holding ) .
Under Goguryeo , the dynasty 's territory extended southward into Korean peninsula , and Dongducheon became part of the kingdom in the form of naeulmae hyun ( a certain form of ancient village land holding ) .