The improved use of iron technologies and new trade networks with Europe via the Portuguese lead to the development of larger, more centrally organized states, including the Ndongo and Kongo kingdoms. The expansion of the Kongo kingdom, the largest state in Central Africa, is the result of diplomatic collaboration with Portugal, control of important trade routes, and the wealth of natural resources within the Kongo territory. A historically unique religious, cultural, and artistic syncretism occurs as a result of the early phase of this cordial and primarily equitable relationship to Portugal.