The position of the ruin on the foreland of the Little Carpathians, looking out on the Záhorie valley speaks volumes about the original function of the Plavecký castle. The Little Carpathians and the area of Záhorie in the foreground have been the frontier area of the Hungarian kingdom ever since the early Middle Ages, which, due to the complicated relationships with its western neighbors, had to be extensively fortified. In the early stages of the kingdom, protection of the border was largely provided by entanglements blocking the passage through the mountain ridge and by tribes of border guards, who were the only inhabitants of settlements in this otherwise barren area of the Záhorie valley.
From 13th century, a gradual population of the flatland under the mountain began and the protection of the kingdom was taken over by solid stone castles, build on the ridge of the Little Carpathians. During the 13. and 14 century, throughout a span of about 100 kilometers of the mountain, from the Danube to the Váh area, about 15 castles had sprung into existence. This firm chain, fittingly called the “Maginot line” of the middle ages by the Moravian researcher M. Plaček, was completed by a chain of smaller guard castles and by lower castles in Holíč, Skalica and Šaštín.
Together with them, a strong defense line was made up by the castles Pajštún, the castle near Kuchyňa, Plavecký castle, Korlátka, Branč and Čachtice. These castles stood on the outer hill parts of the Little Carpathians from which they controlled the space in the foreground and access to the hill passes. Further points of support were the castles in Bratislava, Devín, Dračí Hrádok castle in Borinka, Biely Kameň in St. Jur, Ostrý Kameň and Dobrá Voda, which blocked the passage of important roads though mountains. The network of strategic guard points was completed by the castles Pezinok, Červený Kameň and Smolenice, built on the inner side of the Little Carpathians.