Short answers, pulled from the story.
The history of philosophy is the systematic study of the development of philosophical thought. It focuses on philosophy as rational inquiry based on argumentation, though some theorists also include myth, religious traditions, and proverbial lore.
Western philosophy began in Ancient Greece in the 6th century BCE with an inquiry into the fundamental nature of the cosmos. It spans more than 2,500 years and continues to evolve today.
Thales, who lived around 624 to 545 BCE, is often regarded as the first philosopher. He sought to describe the cosmos through a single first principle, an arche, and identified water as the primal source of all things.
The main non-Western traditions are Arabic-Persian philosophy, Indian philosophy, and Chinese philosophy. Arabic-Persian philosophy peaked during the Islamic Golden Age, Indian philosophy is rooted in the Vedas, and Chinese philosophy centered on right social conduct, government, and self-cultivation.
Philosophy in the 20th century is usually divided into analytic philosophy and continental philosophy. Analytic philosophy dominated English-speaking countries and emphasized clarity and formal logic, while continental philosophy was more prominent in Germany and France and covered movements like phenomenology and existentialism.
After the Islamic Golden Age, the influence of philosophical inquiry waned partly due to Al-Ghazali's critique of philosophy. In The Incoherence of the Philosophers, written by Al-Ghazali who lived from 1058 to 1111, he argued that many philosophical teachings contradicted Islamic faith and should be subordinate to mystical intuition.