The point is that they are applying the term "civilization" to it on the assumption that what they see is writing. Right now I think that is a bridge too far based on what they have uncovered but certainly worthy of further investigation.
If a culture builds primarily out of mud brick and then dies out the mud brick will eventually dissolve even as a result of sporadic rains. If it rains once a year in a century that is 100 rain storms and trust me, when it rains in the desert it fucking rains! A town 30 miles west of here got smashed by flash floods a couple of nights ago. What lasts is stone and not every culture develops in an area where usable building stone exists or is easily attainable. I was just having an email exchange with a buddy in Holland who asked about the utility of covered wooden bridges in New England. The reason was to keep the rain/snow out. Much easier to replace the roof than the bridge. He noted that in Europe they built bridges out of stone which require less maintenance. While true, colonial and post-revolutionary America lacked the road infrastructure to move large quantities of stone. So they maintain the covered bridges which still exist to this day.
If a culture builds primarily out of mud brick and then dies out the mud brick will eventually dissolve even as a result of sporadic rains. If it rains once a year in a century that is 100 rain storms and trust me, when it rains in the desert it fucking rains! A town 30 miles west of here got smashed by flash floods a couple of nights ago. What lasts is stone and not every culture develops in an area where usable building stone exists or is easily attainable. I was just having an email exchange with a buddy in Holland who asked about the utility of covered wooden bridges in New England. The reason was to keep the rain/snow out. Much easier to replace the roof than the bridge. He noted that in Europe they built bridges out of stone which require less maintenance. While true, colonial and post-revolutionary America lacked the road infrastructure to move large quantities of stone. So they maintain the covered bridges which still exist to this day.
