Please answer a question about the following article about Chinese characters:

Based on studies of these bronze inscriptions, it is clear that, from the Shang dynasty writing to that of the Western Zhou and early Eastern Zhou, the mainstream script evolved in a slow, unbroken fashion, until assuming the form that is now known as seal script in the late Eastern Zhou in the state of Qin, without any clear line of division. Meanwhile, other scripts had evolved, especially in the eastern and southern areas during the late Zhou dynasty, including regional forms, such as the guwen ("ancient forms") of the eastern Warring States preserved as variant forms in the Han dynasty character dictionary Shuowen Jiezi, as well as decorative forms such as bird and insect scripts.

What is guwen considered as?
ancient forms