Complex sentence: In the mid- 2nd millennium BC, a third wave arrived, associated with the Apenninian civilization and the Terramare culture which takes its name from the black earth (terremare) residue of settlement mounds, which have long served the fertilizing needs of local farmers.
Split into simpler sentences: In the mid- 2nd millennium BC, a third wave arrived, associated with the Terramare culture. Such culture takes its name from the black earth (terremare) residue of settlement mounds, which have long served the fertilizing needs of local farmers.