Place-names are frequently accepted into the language of a new population. The toponymy of the United States illustrates this well. Spanish names are numerous in the South and Southwest—e.g., Florida, San Antonio, Santa Fe, and San Diego, all of which are Spanish names of Roman Catholic saints or holidays. French names occur frequently in the Southeast and the central United States (e.g., La Nouvelle Orléans, changed into New Orleans; Baton Rouge; St. Louis; Louisiana); Dutch names are found in the East (Haarlem changed into Harlem); Indian names are interspersed everywhere; and, finally, English names are superimposed over all the rest. An examination of all these names, which are now used by a mostly English-speaking population, could not fail to yield some information about the colonization of the United States, even if the history were not known.

In the same way, the place-names of Britain reflect its history. Above all, there are Celtic names—e.g., Eboracum (named for a tree), partly translated as Eoforwic, which changed into York. Roman names are also numerous; e.g., Castra ‘military camp’ changed into Chester, and Lindum Colonia ‘Colony Lindum’ (which itself is Celtic, linne + dunom ‘town at the lake’) is now Lincoln. There are, in addition, Anglo-Saxon names (e.g., Whittingham ‘habitation of Hwita’s people’), Scandinavian names (e.g., Badby, in which -by is the Scandinavian element instead of English -bury ‘castle’), and Norman names (e.g., Richmond, from a personal name consisting of rīki ‘rich, powerful’ + mond ‘world’).

Any country’s toponymy consists of various layers. In France there are Celtic names such as Lucodunos ‘shining town’ that became Latinized into Lugdunum and changed into the modern form Lyon; Greek names such as Agathe (Tyche) ‘good (luck),’ which has become Agde; Roman names such as Forum Julii ‘marketplace of Julius,’ modern Fréjus; and old Germanic names such as Clarbec ‘clear brook’ (klar + Bach in German). Most important is the fact that place-names can be used as a source of information themselves, even if other forms of evidence are lacking; for instance, because Moskva (= Moscow) is a Finnish name (Finnish kva ‘water’) and because other Finnish toponyms are present in Russia, the prehistoric presence of Finnish tribes in that location can be presumed. Names of rivers are particularly important for this purpose, because they are very conservative and usually are taken over by a new population. A considerable number of river names in western and central Europe show remarkable similarity (e.g., Esera in Spain, Isère in France, Yser in Belgium, Isar in Bavaria, Jizera in the Czech Republic) and are the only evidence of a pre-Celtic Indo-European population of those regions.

In a similar way, names are also indicative of cultural and political trends. Singapore (Sanskrit Siṃhapura ‘castle of lions’), for example, testifies to the cultural influence of India in the area. Particularly significant in this respect are deliberate changes of names caused by changes in political power, ideology, and so forth. Changes such as Nieuw-Amsterdam becoming New York, or Léopoldville (named after the king of Belgium who acquired the Congo) becoming Kinshasa, are very common. Some cases of renaming do not lack humour: La Roche-sur-Yon in France was rebuilt by Napoleon and renamed Napoléon-Vendée, which was changed to Bourbon-Vendée under the Restoration; during the 100 days of Napoleon’s return from Elba and in the subsequent second Restoration, the cycle was repeated once more, and only the Third Republic restored the old name. Renaming also shows examples of cynicism: Lyon, which had rebelled against the revolutionary covenant, was punished by systematic demolition and a massacre of its inhabitants; the ruins of the city were renamed Commune-Affranchie ‘Liberated Commune.’ Changes of place-names are sometimes made systematically; when the territory called Alto Adige in Italian and Südtirol (South Tirol) in German became part of Italy after World War I, for instance, a systematic effort was made to give or to return to these territories the Italian character in both place-names and personal names. The Russian Revolution brought a change of names that were reminiscent of the old regime and ideology; e.g., St. Petersburg (changed into a more Slavic Petrograd by the tsar during the war) became Leningrad (and then St. Petersburg again in 1991); Tsaritsyn (from tsar ‘emperor’) became Stalingrad (and then Volgograd in the late 1950s); and Yekaterinodar (from Yekaterina [= Catherine], an empress) became Krasnodar (from krasny ‘red’). However, most of the pre-Revolution names were reinstated after the collapse of the Soviet Union in 1991.