Why is the name of the Country Germany in English, Alemania in latin Coutries, and Deutschland at home?

What is the history involved?

Why is the name of the Country Germany in English, Alemania in latin Coutries, and Deutschland at home?
Germany:


From Latin word Germanus, first attested in writings of Julius Caesar, who used Germani to designate a group of tribes in northeastern Gaul, origin unknown, probably the name of an individual tribe. It is perhaps of Gaulish (Celtic) origin, perhaps originally meaning "noisy" (cf. O.Ir. garim "to shout") or "neighbor" (cf. O.Ir. gair "neighbor").





Alemania:


name of a Suebic tribe or confederation that settled in Alsace and part of Switzerland (and source of the Fr. Allemand "German"), from P.Gmc. *Alamanniz, probably meaning "all-man" and denoting a wide alliance of tribes, but perhaps meaning "foreign men" (cf. Allobroges, name of a Celtic tribe in what is now Savoy, in L. lit. "the aliens," in reference to their having driven out the original inhabitants), in which case the al- is cognate with the first element in L. alius "the other" and Eng. else





Deutschland:


The name Deutschland and the other similar-sounding names above are derived from the Old High German diutisc which originally meant "of the people". This in turn comes from a Germanic word meaning "folk" (leading to Old High German diot, Middle High German diet), and was used to differentiate between the speakers of Germanic languages and those who spoke Celtic or Romance languages. These words come from *teuta, the Proto-Indo-European word for "people" (Lithuanian tauto, Old Irish tuath, Old English 镁eod).
Reply:AskAsk practically said it all.


I just want to add that in some Slavonic languages German is Niemiec, Nemet' or 袧械屑械褑. Which would literally translate as "mute". That comes from the fact that all those using Slavonic languages could understand each other to some degree and Germans were the only neighbors that talked in a way not understandable at all. because of that Germany in some of the languages became Niemcy (Polish) or something similar. In Some cases though the land itself goes back to Germany version - like in Russian 袚械褉屑邪薪褟.
Reply:OK It seems you already got the right answer.