Western visitors to Soviet Central Asia frequently hear complaints from the indigenous Muslim population about local Russians' ignorance of Central Asian culture and lack of respect toward it. These are signs of Central Asians' resentment toward Russians who think the conquest of Turkestan and the arrival of Europeans brought Central Asia its first "civilized" culture. Revealing their own insensitivity, many Russians exhibit a sense of frustration with the "inscrutable" indigenous peoples who retain many of their "archaic" or "feudal" traditions. After the Bolshevik Revolution, the First Five-Year Plan started an economic transformation in Central Asia. The greatest changes were the collectivization of agriculture and the sedentarization of nomadic herdsmen. Following the fifteenth century, the importance of the silk routes crossing Central Asia declined, and Central Asia, along with its traditional centers of high civilization, entered a period of cultural and economic stagnation.