600 was chosen deliberately as it is after the collapse of western Rome and before the heavy plough had started to work its miracle. (Also, Livi-Bacci has 600 in a handy table.)
Plough - Wikipedia, the free encyclopedia
Despite a number of innovations, the Romans never achieved the heavy wheeled mouldboard plough. The first indisputable appearance after the Roman period is from 643, in a northern Italian document[2].
Its the flea ... the flea I tell ya. There's your transition from late antiquity to the early medieval period. I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.
