Following the research done after the 2nd World War, Kozjanski  Park was recognised as an important archaeological region. The earliest findings, various stone axes and hoes, are from the late Stone Age (Neolithic period). The findings from the Iron Age (the Hallstatt  period) indicate the change of settlement image at that time, related to the arrival of new inhabitants from the East. Population greatly increased in the Roman period. Although the main Roman road avoided Kozjansko, two important side roads crossed here.

Significant Roman settlements were in Buče, Golobinjek, Prelasko, Dekmanca, and in Hrastje near Bistrica ob Sotli. Their remains are hidden safely underground, waiting to be discovered. During the migration period, Roman inhabitants moved from their lowland settlements to the higher, more distant locations. At that time the area between the Sotla, the Sava and the Savinja came to life.

Two discovered posts, Veliki Vrh above Osredek near Podsreda and Svete gore, reach beyond the local frame. The presence of Germanic people is evident from some minor findings. Svete gore above Bistrica ob Sotli with Slavic necropolis can be dated back to Slavic period. All findings from the above mentioned locations are on display in nearby museums (Posavje Museum Brežice, Regional Museum Celje and others).