Complex sentence: Pierre Abraham Lorillard (1742--1776) was a tobacconist of New York City, who founded the business which developed into the Lorillard Tobacco Company, which claims to be the oldest tobacco firm in the United States and in the world.
Split into simpler sentences: Pierre Abraham Lorillard (1742--1776) was a tobacconist of New York City. He founded the business which developed into the Lorillard Tobacco Company, which claims to be the oldest tobacco firm in the United States and in the world.