The Talarian Empire is a relatively small conglomeration of star systems loosely affiliated with one another. Their culture is rigidly patriarchal in nature and women are viewed as being weak and subordinate to their male counterparts. The Talarian warships and other militia elements are crewed exclusively by men, which has led to friction between the Federation and the Talarian Empire when a vessel commanded by a female Captain encounters their craft. Their aggressive nature extends not only toward the Federation, but to all of the neighboring powers for which they share a border. Their dealings with Cardassians has been especially volatile in the wake of the Dominion War, which saw their borders being redrawn several times as the Talarians pushed into and later were repelled from the Union's space.
Talarian culture is filled with traditions and ritual customs, making it rather diverse even if technologically the Empire lags behind the Federation a great deal. Most of their rituals revolve around testing the males of the species in an effort to make them grow stronger. These customs also tend to nurture a warrior-like mentality, which can be credited as the source for Talarian aggression. The Talarians are also extremely xenophobic, a speculation derived from their unwillingness to touch other species without gloves on.
Talarians are technologically inferior to most Alpha and Beta Quadrant races, using weapon systems that would not pose a credible threat to most advanced vessels that other powers generally operate in the area around the Empire. Despite this inferiority in firepower, Talarian battle tactics do pose a threat to vessels traveling alone, as ambush and hit-and-run tactics tend to be the norm for the Talarians, and have left many vessels stranded or destroyed.
The Talarian Empire, while not in a state of declared war with the Federation, have no qualms about attacking Federation transports, patrol ships, or border colonies. Given that the Talarian government isn't a sovereign state that holds dominion over the entire Talarian people, but a collection of various 'warlords' who happen to share genetic linage with one another, means that dealing with individual Talarians is very much a case-by-case affair. A vessel might be safe from attacks by one clan of Talarians, but prey for several others who have no ties or concern for the clan with which the deal was struck. This is also why the Federation limits their involvement with Talarians as much as possible, since retaliation against the entire Empire would only serve to amass enemies and grudges with various warlord factions rather than lead to any appreciable conclusion of hostilities.