Before it
Transformers were capped around 512 tokens by quadratic attention.
The problem
Documents are longer than 512 tokens, so they had to be chunked and processed separately.
What it introduced
A sliding local window plus a few global positions, giving attention that scales linearly with length.
Why it matters
One of the first practical long-context designs, and the sliding-window pattern Mistral later revived.
What modern models inherit
Windowed attention as a standard long-context tool.
What came next
BigBird added random attention; Mistral used sliding windows in 2023.