Two important developments provided incentives for European exploration. First ,Europe's population grew significantly in the fifteenth century. The Black Death had devastated Europe's population in the mid-fourteenth century, but, 150 years later, Europe's population had rebounded. The expanding population meant increasing land values, a general increase of prosperity, and an expansion of commerce. Growing trade led to advances in shipbuilding and navigation, which made long sea voyages more feasible. The search for new goods and markets provided a powerful impetus to exploration. Second, with the rise of nation-states, European monarchs had the power, wealth, and desire to sponsor explorations that would develop trade and further enrich them and their countries.Moreover, Muslim control over the trade routes to the east resulted in rising prices of eastern goods. At the same time, however, the Islamic world was not a significant sea power.Portugal and Spain, which had struggled for a long time against Muslims in the Mediterranean, had incentives to seek trade routes by sea to the east. Further, long and bitter wars with the Moors had contributed to religious fervor among the Iberians. Christopher Columbus, for example, recited vespers every evening, led his crew in religious observances,and (although he never took monastic vows) sometimes wore the habit of a Franciscan monk.