My Schoendorf line lived for several generations in Peppenkum . Although now a part of Germany, this area was ruled at various times by both France and Bavaria. Records for this predominantly Catholic area are written in at least three different languages, Latin, French and German, depending on the period and context of the document. For example, I have three different documents (all available at the Family History Library). The first is from a marriage record in a church register from 1782 for Johann Georg Schoendorf and Catherine Conrad.
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Next is the marriage record for their son Johann Schoendorf and his wife Anna Maria Klinlger from 1817.
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You may have noticed the similarities between the French and Latin words for year an and anno and those for thousand mil and millesimo. This is because French, like all Romance languages, descends from Latin.
The final record, from 1866, is the civil registration of the birth of Caspar Schoendorf, the grandson and great grandson of the above couples.
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Because English is a Germanic language, you will notice the similarities between German and English. The word Jahr, where the initial J is pronounced like English Y, is similar to the English word year, and tausend is very close to thousand.
The first few words in all three documents contain the same two words, "year" and "thousand". Think of these as keywords; since you are very likely to encounter them in a document, they can help you identify the language. It may not help for every record, but it is at least one way of narrowing down the possibilities.