Which manuscript confirms that the people of Gojoseon and the Huns are brothers?

What evidence indicates that a saber with a golden hilt, found during excavations in the Korean city of Gyeongju, was made on the territory of modern Kazakhstan? How did the Turkic Khaganate help the kingdom of Goguryeo? Which manuscript confirms that the people of Gojoseon and the Huns are brothers?