Complex sentence: The post in Russia in the nineteenth century was a monopoly of the state through the Imperial Post, however, official post offices were restricted to towns and some large villages, leaving most rural areas a long distance from the nearest post office.
Split into simpler sentences: The post in Russia in the nineteenth century was a monopoly of the state through the Imperial Post. Most state post offices, however, were in towns and some large villages, leaving most rural areas a long distance from the nearest post office.