drawing out thin wires, twisting and laminating them, plaiting them into complex well designed shapes such as necklaces, bracelets and hooks for fishing, needles for sewing and such. These products attracted interest and demand from far off ethnic groups, creating trade opportunities and traders amongst the Luba people. This trade and all economic activity in the villages of Luba people had a tribute system, where a portion of the hunt, fish or produce was given to the lineage head or the people guarding the borders. These were natural borders, such as that created by waters of Lake Upemba, where passage across required channels and bridges. The movement into and out of the Luba people lands was thus controlled and taxed. Luba Empire Around 1500, possibly earlier, the Luba people began to coalesce into a single, unified state which historians now call the Kingdom of Luba or Luba Empire. The kingdom grew and became more sophisticated over time, reaching its peak between 18th to 19th-century. The demands, raids and violence of the 19th-century slave and ivory trade by the European colonial empires such as Belgium and the Arab-Swahili chiefs such as Tippu Tip and Msiri, states Thomas Reefe, "tore the Empire apart" and ended it. The political sophistication of the Luba Empire was the adoption of two layers of power, one of Balopwe (hereditary kingship) and another a council of royals or elders. These provided governance stability through mutual balancing, when there were disputes of succession from death or other causes. This idea was adopted by the neighboring Lunda people and other ethnic groups. The development and evolution of the Luba Empire, and the life of Luba people therein, has been unclear. This is in part because the Luba people were an entirely oral tradition culture where knowledge and records were verbally preserved without a written script. The orthography for the Luba language, called kiLuba, was invented in the 19th century, and thus early information about the Luba Empire has been derived from documents written by others usually hostile and only aware of the communities at the Luba Empire's border, or by the Luba people only in the late 19th-century and the 20th-century after the best decades of the Empire were long over. The later written texts suggest that the Luba people had developed sophisticated literary traditions around their concepts of good and evil, and integrated these concepts and their religious