Sheep and goats were the first dairy animals; oxen were first domesticated as working and draft animals and were only later used for milk. The cheese was first created from sheep and goat’s milk and was soon given the name Pecorino. It is only recently that the word Pecorino has been applied to refer specifically to sheep’s cheese. Initially the word pecu was used to denote livestock in general. For sheep the word ois was in use, from which later the Latin ovis and the Italian ovino would derive. Livestock in ancient Greece was generally sheep and goats, woolly animals whose fleece was called pòkos. In Latin, livestock in general was known as pecus and was later qualified as pecus ovilium, meaning sheep. The importance of livestock, pecus, gave rise to the word pecunia, meaning money or wealth. The term caseus pecorinus was recorded in the 4th or 5th century AD. After the turn of the Millennium the terms pecora and Pecorino were established. The origin of Pecorino cheese dates back to the first domestication of sheep, although it is not easy to put a date to domestication or cheese-making. In Mesopotamia in the 21st century BC, prehistory was already documented and the rearing of sheep was already highly specialized.