Within the Indo-European language tree, Dutch is grouped within the Germanic languages, which means it shares a common ancestor with languages such as English, German, and Scandinavian languages. All Germanic languages are united by subjection to the sound shifts of Grimm's law and Verner's law which originated in the Proto-Germanic language and define the basic differentiating features from other Indo-European languages. This assumed to have originated in approximately the mid-first millennium BCE in Iron Age northern Europe.
Which language tree groups Dutch with English? What group of languages have to comply with Grimm's law? In what age did the sound patterns that distinguish Germanic languages develop? Along with Grimm's law, what's the other rule for Germanic-sounding speech called? What does a language need to share with the group in order to be classified as Germanic?