The phrase "postwar period" refers to the time after a war has ended. It describes the period when the conflict is over, and the process of rebuilding, recovery, and establishing peace begins. Full definition
The results were probably the most original series of paintings of the immediate postwar period in American art. (visual-arts-cork.com)
He believes that we are seeing the onset of global instability again, after the brief and unusually stable postwar period in which warfare now generally means civil wars. (newscientist.com)
Since the immediate postwar period, the most significant extension of the state has taken place under the current Labour government. (theguardian.com)