Extract the answer to the question from the following context. Question: what is the last era mentioned? Context: During the 16th and 17th centuries slave traders began to raid the region as part of the expansion of the Saharan and Nile River slave routes. Their captives were slaved and shipped to the Mediterranean coast, Europe, Arabia, the Western Hemisphere, or to the slave ports and factories along the West and North Africa or South the Ubanqui and Congo rivers. In the mid 19th century, the Bobangi people became major slave traders and sold their captives to the Americas using the Ubangi river to reach the coast. During the 18th century Bandia-Nzakara peoples established the Bangassou Kingdom along the Ubangi River.
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Answer: 18th century

Extract the answer to the question from the following context. Question: How is the fnal part of a treaty marked? Context: The end of a treaty, the eschatocol (or closing protocol), is often signaled by a clause like "in witness whereof" or "in faith whereof," the parties have affixed their signatures, followed by the words "DONE at," then the site(s) of the treaty's execution and the date(s) of its execution. The date is typically written in its most formal, longest possible form. For example, the Charter of the United Nations was "DONE at the city of San Francisco the twenty-sixth day of June, one thousand nine hundred and forty-five." If the treaty is executed in multiple copies in different languages, that fact is always noted, and is followed by a stipulation that the versions in different languages are equally authentic.
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Answer: in witness whereof" or "in faith whereof,"

Extract the answer to the question from the following context. Question: Why are the laws not specific? Context: There are 17 laws in the official Laws of the Game, each containing a collection of stipulation and guidelines. The same laws are designed to apply to all levels of football, although certain modifications for groups such as juniors, seniors, women and people with physical disabilities are permitted. The laws are often framed in broad terms, which allow flexibility in their application depending on the nature of the game. The Laws of the Game are published by FIFA, but are maintained by the International Football Association Board (IFAB). In addition to the seventeen laws, numerous IFAB decisions and other directives contribute to the regulation of football.
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Answer:
allow flexibility in their application depending on the nature of the game