From "A Short History of Ancient Carthage"

The early matriarchy was, from all available evidence, a strongly controlled oligarchy, one that may be seen as brutal by today's standards. At Carthage and several other early city sites, physical evidence of mass graves has been found. Interpretations differ, but most archaeologists suspect either large-scale ritual sacrifice or the extreme and prolonged use of forced labor. Modern dating techniques reveal no steady pattern in the killings, but at least eight distinctive strata of human remains have been found, with gaps of at least two to three hundred years between. Estimates of the total buried in Carthage's mass grave alone vary widely, but even the most conservative historians estimate at least one hundred fifty thousand, with others claiming close to half a million.

It is unlikely that we ever really know what life was like in early Carthage before the widespread use of written records, as such, the mass graves remain a troubling, yet inexplicable, mystery.