What effect did nomads have on the song dynasty

What happened as agriculture became entrenched in the south ?

During the era of european expansion, what was the biggest reason for spain’s push for exploration?

Which of these did the soviet union do in 1961? it built a wall through berlin to keep people from moving to the west. it used force to destroy a wall the united states had built in berlin. it convinced the british and french to merge their zones in berlin with the soviet zone. it threatened to bomb berlin if the united states did not leave within 30 days.