Original Colonial Empire? I think not.
"Portugal was also the original colonial empire ..."
So it's older than, say, ancient Egypt? Sumer? China? The Mongols? The empire of Islam under the Caliphs? The Huns? The Tripolis (what most American think of as the Aztec Empire)? Shall I go on?
Maybe the original writer meant, "... original European colonial empire ..."? Nope, because Portugal is not older than the Roman Empire--you know, the one the word "Empire" was coined for?