In 1923 Ernst Herzfeld was the greatest living scholar of the Persian Empire, that ruled in the Middle East from 612BC until it was defeated by Alexander the Great in 330BC. That year Herzfeld set out on his last major expedition. It would last more than 10 years. It would make crucial discoveries about this misunderstood civilisation, and it would end in personal disaster. A German expedition in the 1920s was of necessity small-scale, operating with little or no money. The defeated power in WWI could no longer afford such "luxuries". But this was also an opportunity: the colonial powers - Britain and France - were not popular with the local governments in the region. By teaming up with oil money from America, Herzfeld could gain both political, and financial, support - enough to continue his work. And what discoveries he made: Herzfeld excavated the administrative centre of Persepolis, the Persian imperial capital, uncovering thousands of clay tablets which described in detail the administrative system and the trade networks of the Empire. Far from being the tyranny described by their Greek conquerors, this was evidence of a tolerant and cosmopolitan Empire that took the best from all the peoples it ruled. If Herzfeld found the information, his assistant Friedrich Krefter discovered the treasure - the solid gold plaque forged for the great King Darius to acknowledge his glory. But Herzfeld was Jewish, and while he was in Persia his country was taken over by the Nazis. Once again, distrust and prejudice ruled; stripped of his professorships by 20th Century tyranny, he was even accused of theft of Persia's national treasures. Politics refuses to spare the region today, as archaeologists - notably from Australia - continue to research the ancient Persian Empire, trying now to understand how this Empire extended its power so many hundreds of kilometres from the capital.