Westeros: seven kingdoms under a fragile Iron Throne; winters and old threats still whispered.
Houses Stark, Lannister, Baratheon, Targaryen (in exile), Greyjoy, Tyrell, Martell and others drive power.
Beyond the Wall: wildlings, and something colder. Across the Narrow Sea: exiles and sellswords.
You are still early in Season 1. Prior seasons (if any) are fully in force; this season's finale geometry is not.
Season 1 is the fall of honorable order: Ned's investigation of Jon Arryn's death exposes that Joffrey, Myrcella, and Tommen are Jaime and Cersei's children, not Robert's.
War begins in earnest: Robb wins early field victories; Jaime is captured by the North; Tywin maneuvers from Harrenhal direction.
Focus on who wants what, who is allied, and which institutions are pressuring the cast.
Season 1 path through S01E02: E1 "Winter Is Coming" → E2 "The Kingsroad".
Cutoff discipline: every fact above ends at S01E02. Do not import anything from S01E03 ("Lord Snow") or later.