Sometime in the second half of the fifth millennium BC, several people were talking and working together inside a house in a small village in what is now north-eastern Bulgaria. The village was now well established, having grown up over a long period of time, through many generations of people’s births and deaths and many episodes of abandonment of old crumbling houses and replacement with new ones. The village sat next to a thin stream which, having risen in the mountain foothills to the south, wound its way northwards, past the village, eventually joined by other streams before emptying into a larger river which, in turn, swung 100 km or so to the east before it emptied into the Black Sea.