La Guera was part of the Spanish colony that would eventually become known as Western Sahara (considered part of Northern Africa in the UN Geoscheme) in the early part of the twentieth century. In 1920 and again in 1922, Spain used special La Aguera-only postage stamps.
In 1920, Spain simply overprinted existing stamps from its larger Río de Oro colony with ‘LA AGÜERA’. The 1, 4, and 10 peseta versions of these overprinted stamps (the highest three denominations) are the most valuable.
In 1922, stamps were issued especially for La Guera; these were inscribed ‘SAHARA OCCIDENTAL / LA AGUERA’. The same denominations as the 1920 overprints are the most valuable of these 1922 La Aguera stamps.
When browsing La Guera postage stamps for sale, note that the name of the territory in German is La Gouira; in French, Lagouira; and in Dutch, La Gouèra.