NZinga MBandi was a deceased NDongo "ngola"'s sister. Bypassing the reigning ngola, she negotiated a peace treaty with the Portuguese. The treaty gave substantial trade and religious advantages to Portugal, but delivered Mbandi the throne in NDongo. After five years, she had to flee from Portuguese troops to Matamba. She became queen of Matamba, a kingdom which was traditionally led by women, and turned it into the most powerful state in the region, and a big exporter of slaves. Matamba, and neighboring Kasanje, had monopolies in the slave trade, and started falling apart in the 19th century when this trade lost in importance. The rise of a new trade in ivory, rubber and wax, which avoided the old monopolies, reduced the power of central authority in the Ambundu states in this century.