Interior to this 4:1 resonance, asteroids in low inclination orbits are, unlike those outside the 4:1 Kirkwood gap, strongly influenced by the gravitational field of Mars. Here, instead of Jupiter's influence, perturbations by Mars have, over the lifetime of the Solar System, thrown out all asteroids interior to the 4:1 Kirkwood gap except for those far enough from Mars's orbital plane where that planet exerts much smaller forces.
Located inside a 4:1 resonance, asteroids in low inclination orbits are subject to strong influences from Mars. In contrast to Jupiter's impact, Mars's gravitational forces have, throughout the Solar System's history, removed all asteroids within this region except those at sufficient distances from Mars's orbital plane.