Isaiah represents the Syria-Israel coalition by their capital cities, standing for the countries and their kings. As the capital city of the northern kingdom, the city Samaria lent its name to its dependent lands so that Samaria is both city and nation in biblical texts. Before the child reaches the age when he can talk plainly (an intentionally vague time period, but one that would be generally understood), the Assyrians will destroy Syria and Israel.
Literature: Timing the Assyrian invasion to the child’s ability to call for his mother and father reinforced the significance of his parentage (v. 3). This child calls, not only as a normally developing little boy, but also as the embodiment of prophecy.