The Saarland is an area in western Germany boarding France. It has traditionally been one of the major industrial areas in Europe with a skilled and energetic workforce and ready access to coal, which in the nineteenth and early twentieth centuries was the main fuel used in manufacturing. When WWI ended (and Germany collapsed more than was defeated), the Treaty of Versailles was signed by the Allies and the Germans and Austro-Hungarians. The Treaty was ostensibly intended to reduce Germany’s industrial power to make future wars impossible. The reality of the Treaty was to impose a difficult peace on Germany, with huge reparations and loss of territory. The Treaty of Versailles contained the seeds of its own destruction as Germany’s anger at the Treaty was one of the main reasons the Nazi’s were able to come to power.
One major section of the Treaty of Versailles was to take the Saarland from Germany, make it a French Protectorate, and have the coal revenues from Saar coal mines go to France to help pay the huge war reparations that Germany owed under the terms of the Treaty. The stamps of Saar make this interesting piece of history come alive. Saar issued stamps from 1920-1935 when a plebiscite was held, and Saar voted to be reunited with Germany. After WWII, Saar again became administered by France and issued its own postage stamps.  In 1955, the French ended administrative control of Saar, and Saar no longer issued stamps.
Saar is a philatelic delight. It is a part of the fascinating history of the French/ German conflict that has been going on for over the entirety of recorded history—the Roman Empire included France but not what is now Germany, and the border was fought over constantly (not much has changed since then). And the stamps are well designed, colorful, and, for the most part, not too expensive. Making a collection of Saar stamps is challenging but not overwhelming. And if you want to have a serious specialty, again at not a ridiculous cost, try Saar. There are thousands of varieties of the major stamps listed in the Scott and Michel catalog, many very scarce, but most are harder to find than they are to afford.