Final answer:
Nomadic tribes on the northern and western frontiers engaged in activities such as tending to animals, migrating to better grazing areas, and crossing national borders. Modern industrialization and the establishment of nation-states affected their traditional way of life.
Step-by-step explanation:
The nomadic tribes who lived on the northern and western frontiers often engaged in various activities. They tended to goats, sheep, camels, cattle, and occasionally horses, and had to find grazing land for their animals, which sometimes brought them into conflict with settled agricultural peoples. They also migrated to better grazing areas during the hottest and driest seasons. In addition, modern nation-states objected to nomads crossing their borders at will, considering them a threat to national security and sovereignty. As nations industrialized, nomads' access to grasslands and water sources was jeopardized.