The historical roots of Kazakhs reach back to ancient nomad cattle breeding Sak society during the period between 8 and 3 centuries, B.C.
The formation of Kazakh statehood began in the Sak society and received further development in the line of successive connections with the tribes of Usunies in the Zhetysy region and the Kanglys on the Syr-Daria river form the end of the 1 millenium B.C. through the first half of the 1 millenium A.D.
The political organization created by this civilization was, in essence, the first proto-Turkic state formation on the territory of Kazakhstan. Large Turkic-speaking communities and states began to take shape with advancement of the Huns from Inner Asia to the steppe zone of Central Asia in the II century B.C.
You may enjoy more content about the Kazakh Khanate on the History of Kazakhstan portal.