The United Arab Republic was the official name of the stamp-issuing union between Egypt and Syria beginning in 1958. This immediately followed the short period when Egypt, on its own, had first become a Republic. Syria left the United Arab Republic in 1961; curiously, Egypt kept the name officially for itself until 1971.
Egyptian stamps from this period were at first imprinted ‘UAR’ or ‘UNITED ARAB REPUBLIC’ (in English), with ‘EGYPT’ appearing in smaller letters nearby. After the first couple years, the word ‘EGYPT’ was dropped altogether; after 1961 this would have been superfluous anyway.
Graphically, the United Arab Republic stamps of this era began to take on a more familiar, modern look, with more colors, art deco elements and compositions, and crisper, clearer printing.
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Collecting and buying United Arab Republic stamps today can be a snap; the pieces are widely available and aesthetically attractive. It is generally pretty simple to actually get a multi-stamp lot of these stamps for relatively cheap, after which you can keep the ones you like for your collection and trade the rest to other collectors.