chrysargyron

In the Eastern Roman Empire, chrysargyron, also called chrysargyrum or collatio lustralis, was an unpopular tax levied every four years, on people of all stations, rich and poor, slaves and freemen; even on animals and pets. It was collected during the first hundred and seventy years of the Eastern Roman Empire. The term originated from the Greek words for gold (χρυσος) and silver (αργυρος), which initially were the required forms of payment.