The establishment of a new capital marks a major turning point in the history of the Kingdom of Israel. After a period where the kings of Israel simply ruled from the same locations as their predecessors, King Omri decided to break from tradition. In the seventh year of his reign, he sought to firmly secure his rule by building a new, permanent royal city that could rival Jerusalem in both size and status [מצודת דוד, ביאור שטיינזלץ, אברבנאל].
To realize this vision, Omri purchased a mountain from a man named Shemer, the original owner of the land [מצודת ציון]. While the area became known as Samaria, the primary approach among commentators is that this name was only applied to the mountain in hindsight, after the city was fully constructed [מצודת דוד, חומת אנך]. The site itself was not entirely empty prior to the sale; a large city already stood on the mountain. Omri's project involved fortifying the existing structures and completely rebuilding the area to suit a royal center [רלב״ג, רד״ק].
Omri chose to name his new capital after Shemer. Naming a royal city after an ordinary mortal, who might have even been a wicked person, highlights a fundamental spiritual difference between the capital of Israel and the capital of Judah. While Jerusalem's name represents awe and perfection, Samaria carries a purely secular name [מלבי״ם].
Despite its mundane foundation, the building project was highly successful, and the new capital stood firmly for many years [ביאור שטיינזלץ]. The Sages praised Omri for his initiative in developing such a large and important city in the Land of Israel. As a reward for this contribution, his dynasty was granted the privilege to rule for three successive generations. Ultimately, Omri fulfilled his ambitious goal of making Samaria the permanent administrative heart for the kings of Israel, mirroring the role Jerusalem played for the kings of Judah [אברבנאל].