michael spence is directing the excavation. he has just found some pottery in one of the ruins. spence: it's painted here. you can see that there's red paint over most of the interior except up along the rim. there's a little bit up there, too. it's going to be very delicate, very fragile. and i'll try and reassemble it and see if there's any sort of a design on it, or if it's just a solid red. we've been picking up pottery from all over the fields. and in examining the pottery, we saw that a high proportion of it was foreign to the city. and we knew from the work of others that it came from the oaxacan area. it turns out that actually it was produced here. the people moved here, but they continued to make pottery in their home tradition. keach: the pottery indicates that this compound may have been occupied by traders from far-off monte alban, an indication of a complex economy here. bill sanders. one of the aspects of culture that is extraordinarily variable is the economy. economy means the ownership of property and the production and distribution of goods. there are cultures