In early history, Mauritania was more known for its transsaharian camel trade roads with more fertile oasis, as the climate was a little cooler than now. This region was mainly occupied by African tribes, followed by Arab ones. Portuguese settlements of Ras Nouadhibou (now in the Western Sahara/Mauritania border) & Ras Agadir in 1442 started to destabilize this traditional trade, but the French colonies definitely kept all the regoinal trade through Senegal, Ivory Coast & Dahomey. French colonization started subduing local emirates close to the Senegal colony, in order to keep a continuity with French Algeria. From 1902 to 1934 the remaining Mauritania is conquerred, and a few parts shared with Spain. Anyway French colons ignored most of the country. Mauritania became independant in 1960.
Since then the country was ruled under a unique party regime, up to 3 consecutive putsches in 1978, 1980 & 1984. In 1991 the unique party system is theoretically abandonned, but electoral frauds made the opposition unable to win any election. From 2003 to 2005 3 putsches occurred (one putsch every year, but only the last one succeded) and the junta tried to install a more democratic system. This finally failed after a last putsch in 2008, as the new civil power was unstable. The junta chief finally left the army to te candidate and elected (like a few months ago in Egypt), and his government gave concessions to stay after the Arab Spring in 2011. Just note there remained a high level of racial, tribal and cast segregation in the country, despite their criminalization in the last decade (mainly in 2007 and 2011).
During the French colonization, Mauritania depended on the French Franc, followed by the CFA Franc, up to 1973 when Mauritania withdrew from the BCEAO and created its own currency: the Ouguiya, which particularity is to have only a 1/5th subdivision (the Khoums). In 1973 were introduced 1/5 ouigiya (1 khoums), 1 ouigiya, 5 ouigiya, 10 ouigiya and 20 ouigiya coins. In 1974 the 1 ouigiya coin was a little modified (if anyone understanding Arab can say why there is a word added on the coin...). In order to reduce minting costs all coins were updated in 2004 (all coins were plated since then) except the 1 ouigiya which was discontinued, this discontinuation was followed by the 5 ouigiya and the 20 ouigiya, in order to modify them in 2009 (new colour for 1 ouigiya, new size for 5 ouigiya, new bimetallic coin for 20 ouigiya with its brass-clad rim and its nickel-clad center, which is a quite uncommon combination). At least a new bimetallic 50 ouigiya coin is introduced in 2010.
There were no more khoums coinage after 1973 because of its low value (actually less than 0.06 eurocent), and the 1 ouigiya coin may follow the same destiny after its last emission in 2009 (less than 0.3 eurocent).
https://en.numista.com/catalogue/mauritanie-1.html