First of all the albanian migration in the balkan peninsula isnt recorded because there never was one . And there is a theory that albanian , greek and latin , two of them come from one of them ( e.g  albanian and greek come from latin ) , but the only reason why there are slavic words is because when the slavs migrated the language got "mixed up" . And as you might know the albanian alphabet was only established in 1908 (the congress of manastir)