The Hellenistic period refers to the era in ancient history that began after the death of Alexander the Great in 323 BCE and lasted until the rise of the Roman Empire around 30 BCE. This period is characterized by the spread of Greek culture and influence across a vast territory, including parts of Europe, Asia, and Africa, due to Alexander's conquests. During the Hellenistic period, there was significant advancement in various fields such as art, science, and philosophy. Notable figures include the mathematician Euclid and the astronomer Aristarchus, who contributed to the understanding of geometry and heliocentrism, respectively. The blending of cultures led to the development of new ideas and innovations that shaped the future of Western civilization.