Older iron ages in this areas lasted between 750 and 300 years BC. In majority of Europe, as well as in northern Croatia, during this time it was observed appearance of the wide complex of 'Halstat' culture. Basic characteristics of this culture are first extensive production and usage of iron in the area of Europe, and community structure where military aristocrats are dominant class, led by some kind of dukes.

In this period, larger centres appear, which are formed as fort settlements. They are dominant in the certain areas, which then become the station of local rulers. Their power and wealth lied in the controlling of local commercial roads, through which the raw materials travelled towards progressive Mediterranean cultures, primarily Greece and Italy, and from there a arrived valuable items that were not seen before in area of middle Europe, made by top craftsmen. Same way, the power of certain communities, and their rulers in forts, depended on the control of natural resources, as well as on the warrior's power, what was the pillar of the entire society.

In the area of north Croatia, that is Slavonia, phenomenon of 'Hastate' culture is marked by the cultural group Martijanec-Kaptol. One of the most important locations of this cultural group is above Kaptol, nearby Požega. The basic characteristic of this cultural group is burring distinguished members of the society into large grave mound - tumule. Although they kept the cremation of the dead as a fundamental ritual (same as in the late Bronze Age in this area), the important change of the society structure is in the monumental tomb constructions, whose building requested firm hierarchical organization and large amount of invested work.

So far, on this locality two such necropolis were found, and one larger settlement. Of a special value is finding place of a ceramic vessels in Kaptol. The vessels are of unique shape with amazing decorations, and represent one of the most beautiful examples of this time in entire Europe.

Majority of fine vessels is covered with layer of glow graphite, what gives them special metal glow. This very colliery that was exploited still in the 60ies years of 20th century, represented one of the important foundation of wealth and power of the Kaptol dukes.

Certainly, the most famous and far more beautiful forms found in Kaptol tombs are urns, decorated with bullheads. Although they were not perfectly made and covered with simple geometrical decoration, those urns have a unique beauty that was not found anywhere in the Europe of this time. This very specimen was found in necropolis Gradica, where the exploration just started. The beauty of this urn is just the indication of what is under the Kaptol duke's tombs.