The Byzantine Empire contained almost all the land surrounding the Mediterranean Sea, as well as areas around the Black Sea. There were periods of both prosperity and decline in the Byzantine Empire. The Emperor Anastasius I "laid the foundations for Byzantine prosperity." His successors took back previously conquered lands, leading to growth of the Empire. Later, years of volatility with neighboring Muslim empires led to "Arab invasions and raids." When these raids slowly became less and less, the Byzantine Empire began to prosper again. Growth in population also contributed to the prosperity of the empire. More land was cultivated for agriculture, which also helped the Byzantine Empire to prosper. Trade increased and silk production boosted the economy. A provincial mint led to an increase in the money that was in circulation. The Byzantine coinage became the "most stable and desirable" to be used for trade.