Simplify the following text for a Grade 13 native English-speaking person.
Original: An initially independent and later autonomous state , it existed from the 14th century to 1859 , when it united with Wallachia as the basis of the modern Romanian state ; at various times , the state included the regions of Bessarabia ( with the Budjak ) , all of Bukovina and ( under Stephen the Great ) Pokuttya .
Simplified: It existed from the 14th century to 1859 , when it became one with Wallachia as the basis of the modern Romanian state ; at various times , it included the regions of Bessarabia ( with the Budjak ) and much of Bukovina .