Fraction (%) of planetesimals from each initial formation zone that end up within 1-au-wide semimajor-axis bins at t = 300, kyr for the two-planet model (log scale). We consider implanted objects as those with e < 0.4. In all cases, most bodies formed between 9 and 10 au remain near their birth locations, reflecting a dynamically quiet zone largely unaffected by Saturn’s growth. The prominent blue feature near −7 au corresponds to particles trapped in Saturn’s co-orbital region.