The theme of the gathering is extended in this verse. The outcasts of Israel are the Israelites of the northern kingdom who were dispersed by the Assyrian conquest. However, Isaiah’s mention of Judah being gathered from the four corners of the earth clarifies that Isaiah’s vision extends into the future, including the Babylonian conquest of Jerusalem, which will scatter Judah. Isaiah promises the final gathering, a distant reuniting made necessary by Judah’s dispersion, which would come in historic time a hundred years from his prophecy.