People arrived in the Susquehanna Valley near the end of the last Ice Age more than 12,000 years ago and lived a nomadic lifestyle of hunting and gathering. Around 1000 A.D., the domestication of plants enabled native peoples to live in villages along the Susquehanna River as the area's first farmers, growing corn, beans, squash, and tobacco, while also developing an extensive network of footpaths and engaging in far-reaching trade. The arrival of Europeans brought many changes, and around 1575 the fur-trading Susquehannocks took control of the area, but by the 1690's they were dispersed by their enemies and eventually joined with other refugee peoples to form the Conestoga Indians. The Conestogas then declined until a group of frontiersmen annihilated the last of them in 1763. Imprints of these early inhabitants remain in thousands of unearthed tools, adornments, and pottery, evidence of large villages along the Susquehanna River, and rock carvings in the river, where years ago more than 1,000 petroglyphs could be found from Columbia to Conowingo, MD, and where more than 300 still exist on rocks a short distance below Safe Harbor Dam.