As the solar system was forming, many of the planets lacked defined orbits. Jupiter, the largest planet in our solar system, smashed its way through the solar system. Many smaller planets that existed were destroyed as Jupiter settled into its current orbit. Much of the debris generated by the collisions contributed to the formation of the other planets such as Mars and Earth. Most solar systems have more planets closer to the central star, unlike ours which only has Venus and Mercury. It is very likely that Jupiter is directly responsible for the lack of planets closer than Mercury to the Sun.
Sources:
http://www.pnas.org/content/early/2015/03/18/1423252112
http://www.iflscience.com/space/early-jupiter-was-wrecking-ball-smashed-through-baby-super-earths
http://news.ucsc.edu/2015/03/wandering-jupiter.html
http://io9.com/jupiter-may-have-destroyed-the-solar-systems-first-plan-1693169374