[1] Since its foundation in the High Middle Ages Diefflen was historically linked to the villages of the former "Hochgericht Nalbacher Tal".

[2] Diefflen is assigned to the foreland of Hunsrück and thus to the Saar-Nahe Hills and the Lorraine-Cuesta, the easternmost limb of the Paris Basin.

[3] The Buntsandstein weathered to nutrient-poor, light sandy soils, which are not favorably for an agricultural use and remained largely forested in the history.

The closeness of the forest was broken up there by man, where the Buntsandstein stain-like younger, tertiary sediments, such as the flooded clay were stored.

However, Saar and Prims were only able to transport their material for removal, which fell in large quantities under the climatic conditions of the cold ages, so that it was accumulated on wide valley floors.

The slopes include the flanks of larger and smaller valleys and the walls of young erosion gorges ("Gräthen").

Diefflen is divided into three zones: the floodplain as part of the lower valley of the Prims, the hillside- and gorges-zone and the plateau of the "Dieffler Terrassenplatten".

10) junctions are on the Bundesautobahn 8, that runs 497 km (309 mi) from the Luxembourg A13 motorway at Schengen via Neunkirchen, Pirmasens, Karlsruhe, Stuttgart, Ulm, Augsburg and Munich to the Austrian West Autobahn near Salzburg.

It is a railway junction on the Saar route of the German course (Saarbrücken-Trier-Koblenz) with branch of the Niedtalbahn into the French Thionville and Metz as well as the Primstalbahn.

[17] On the part of the premises of the Dillinger Hütte, which lies on the left side of the Dieffler district, there are six tracks that serve rolling mill 2.

[18] There are two facilities available in Diefflen for the care of infants: In the years 1962/1963 the municipality of Diefflen built according to the plans of the architect Konrad Schmitz (Dillingen) a large new school building with two classroom wings, an administration building with student toilets, a covered break hall, a gymnasium with outdoor sports facilities and a courtyard with an Arboretum in Richard-Wagner-Straße.

[25] He was a baptized Jew and showed his Jewel-friendly policy by the 1755 granted permission to create a Jewish cemetery on the edge of the Dillinger Wald on the bann border of Diefflen.

The initiative was based on the Jews Hayem, Zerf of Worms and Elias Reutlinger, citizens of Saarlouis, who had to pay an annual interest of 25 Lorraine Francs.

In 1964, a burial ground for more than 50 Polish and Russian forced laborers of the Nazi era was created in the back of the Jewish cemetery.

The memorial stone bears the inscription "Homeless and abandoned, they found their last resting place in foreign soil.

After severe damage in World War II, the building was extensively extended in the years 1948-1950 according to the plans of the architects Alois Havener (Saarlouis) and Rudolf Güthler (Saarbrücken) and redesigned in the romanizing or late-antiquing abstraction-historicism.

[27][28][29] Diefflen belongs to the Roman Catholic Diocese of Trier (Ecclesiastical province of Cologne) and to the Protestant Church in the Rhineland.

[30] In 1891, when the old Romanesque church of Pachten was demolished to build a neo-Gothic one, the late antique so-called "Ursusstein" with a Christogram ☧ was found.

Of particular importance for the Christianization of the Nalbach-Valley with Diefflen is certainly the foundation of the Franconian nobles and deacon of the Verdun Cathedral, Adalgisel Grimo.

He determined on December 30, 634 in his will that his possessions in the place Tholey together with the built there by him "loca sanctorum" to the Roman Catholic Diocese of Verdun, which at the time was headed by Bishop Paul, should fall.

Nalbach, which was mentioned as a parish for the first time in the 11th century, belonged in the Middle Ages to the archdeaconry St. Mauritius Tholey and the deanery and land chapter Merzig in the then Archdiocese of Trier.

By a gift of the Archbishop of Trier Eberhard from 1048, a letter of protection of Henry III from 1098 and a letter of protection of Pope Adrian IV of 1154 and by acquiring the rights of the knights of Nalbach in 1331 the Simeonstift of Trier had in the Nalbach-Valley the basic jurisdiction, the tax collection law and the right to fill the vicarages.

However, with the reunification policy of King Louis XIV of France and the construction of the fortress of Saarlouis, here too, as well as in Schwalbach, Reisweiler, Eiweiler and Überherrn, the only superficially Protestantised church ended.