Calisia was a "station" on so-called "Amber Road

Amber Road

The Amber Road was an ancient trade route for the transfer of amber. As one of the waterways and ancient highways, for centuries the road led from Europe to Asia and back, and from northern Africa to the Baltic Sea....

", mentioned by Ptolemy

Ptolemy

Claudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...

, formerly universally identified with Kalisz

Kalisz

Kalisz is a city in central Poland with 106,857 inhabitants , the capital city of the Kalisz Region. Situated on the Prosna river in the southeastern part of the Greater Poland Voivodeship, the city forms a conurbation with the nearby towns of Ostrów Wielkopolski and Nowe Skalmierzyce...

 in Poland

Poland

Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

. Besides the similarity of the names, the identification was supported by the closeness between the latitude

Latitude

In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

 given by Ptolemy (52°50') and the actual latitude of Kalisz (51°45'27").

The validity of these arguments is currently in doubt, mainly due to the identification of Ptolemy's Leukaristos, located at a latitude similar to that of Kalisz, with the name Laugaritio/Leugaritio certainly referring to the town of Trenčín

Trencín

Trenčín is a city in western Slovakia of the central Váh River valley near the Czech border, around from Bratislava. It has a population of more than 56,000, which makes it the ninth largest municipality of the country and is the seat of the Trenčín Region and the Trenčín District...

 in Slovakia

Slovakia

The Slovak Republic is a landlocked state in Central Europe. It has a population of over five million and an area of about . Slovakia is bordered by the Czech Republic and Austria to the west, Poland to the north, Ukraine to the east and Hungary to the south...

 (this identification is confirmed by a rock inscription made in the winter of 179/180 CE by a Roman military unit, and the biography of the unit's commander, M. Valesius Maximianus, carved on his tomb in Diana Veteranorum

Diana Veteranorum

Zana or Diana Veteranorum was an ancient Roman city in Algeria. It was located about 40 km northeast of Lambaesis.Zana was founded in the connection with the settling of Roman veterans in northern Africa under the emperor Trajan . An older Numidian settlement was merged with a new veteran...

in today's Algeria). As Trenčín is much further south than the latitude given by Ptolemy, this identification seems to imply that Ptolemy's data on latitude of places north of the Danube had significant errors, hence making the Calisia-Kalisz identification doubtful.