The Battle of Talisca is one of my favorites. It took place almost as far from Greece as the Siege of Memphis two decades later. It was an aberration: Both armies were isolated, far out of their element, and almost certainly neither actually wanted to fight in a region which neither the Greeks nor Persians ever tried to invade, but I find it all the more interesting because of that. Our chief period source on it is Eurypylus of Miletus (449-394 BCE) who wrote Historia tou Europas ("Inquiries about Europe," or "History of Europe") in or around 415. There is, however, a possible corroboration to be found among the Persepolis Fortification Archive.
According to Eurypylus, after the Battle of Salamis, several Greek and Persian ships were driven northward by a storm up the western coasts of Greece. Their crews beached them on the northern Adriatic shores and disembarked in search of food and directions. The Persians, learning of the Greeks' presence, pursued them, or possibly it was the other way around. Alternately, the two groups ran into each other through blind chance after trying to avoid each other for as long as possible. In any event, they had wandered deep into Europe by the time they finally met in the highlands of what is now Provincia, populated at the time by the Paraseticae.
The Paraseticae were an Indo-European people speaking a language possibly related to Celtic, Illyrian or Germanic. They were an impoverished tribe who subsisted on small farming, herding (mainly of sheep and goats, with small numbers of cattle), and stealing things from their lowland neighbors. Nonetheless the "prince" or chief of the Paraseticae, Golbrantes, sent messengers to two villages telling them to welcome the invaders separately. Eurypylus thinks that Golbrantes had the idea of getting the two armies to fight to the death and then pillaging the dead, but it didn't exactly turn out that way.
War was not the Paraseticae's strong suite. The nearest thing they had to armies were sort of like parties of land-Vikings, but more poorly equipped. They relied on dashing in and overwhelming isolated herders or homesteads, grabbing loot and fleeing back into the highlands while doing as little fighting as possible, and robbing travelers. On top of being too disorganized and few in number to form armies with any clout, one of the most important factors in their inability to wage war was noted by Eurypylus and even Roman writers hundreds of years later to be their limited supply of decent timber trees. The most common tree in Provincia is the so-called brittle oak, whose wood disintegrates when dry and today is a common component of pulp for toilet paper. Most useable wood was used up for looms, tool handles, certain structural parts of houses (other components were made of mud or stone, with thatched roofs), and other places where nothing else would work. As a result their spears were small, thrown javelins were rare because of the risk of breakage and loss, edged weapons usually had grips of bone or horn, and most shields were either hide or woven grass - even wicker or Asian pseudo-wicker are unachievable without a decent resilient wood.
The Paraseticae didn't have a whole lot of metal, either. The largest edged weapons ever excavated from the period are less than 20 inches overall, and no spearheads exceeding the size of a large javelin have been found that aren't of obviously foreign construction. It's possible that relatively wealthy headmen would have been able to equip themselves with looted arms (Provincia borders on areas of the late Hallstatt and La Tene cultures) but the average raider - terms like "soldier" or even "warrior" are not justifiable here - would've been underequipped by the standards of the poorest Greek or Roman skirmisher. No evidence of archery has ever been found in Provincia pre-dating the late Roman period.
The next morning the two armies went ahead and fought just east (or north) of Talisca. Again, both groups were out of their element. Talisca itself was well-defended behind a narrow, fortified pass, so neither force attempted to lodge themselves inside the village, but the uneven and thickly forested ground hindered the hoplites as well as the Persian archers and Phoenician javelineers, while the Paraseticae mercenaries mostly just attacked each other. After fighting all morning with few casualties and no one managing to hold ground, the two groups withdrew to their camps.
At this time one of Mithraphernes' personal retainers, an archer named Aricaspes, convinced him that a mutual retreat would be in their best interests. The opposing captains secretly met in the forest nearer to Talisca and worked out routes back to the Adriatic coast that would avoid their forces crossing paths again. Apollodorus returned to the Peloponnese by the middle of November. Eurypylus says nothing more of the Persian forces, but it's interesting to note that one of the Persepolis administrative tablets, dating to the tenth regnal year of Xerxes (i.e. 477 BCE), is signed by an Arikaašba of Mirkaniya (the Elamite name for Hyrcania). It's possible that this is actually the archer Aricaspes, having returned home and taken up, or more likely resumed, a job as a bureaucrat at Mithraphernes' estate in Hyrcania. Certainly *Arikaspa would be an unusual, though obviously Iranian, name; it appears to mean "whose horse(s) is evil" or simply "bad horse."