Khorasan Dervishes inter-mixed up in the same cultural Christian communities living in Anatolia with immigrant Turkmen groups. They played a vital role in the creation of cultural integrity in Anatolia and in the constitution of central authority. One of the Khorasan Dervishes who arrived in Anatolia was Hacı Bektaş-i Veli, who lived in the XIIIth century. He was born in Nishabur city of Khorasan in Iran and learned philosophy and social and technical sciences in Hoca Ahmet Yesevi Center. He then migrated to Anatolia and settled in Hacıbektaş (formerly called Sulucakarahöyük). He improved his knowledge of philosophy and began to educate students. His system of thought based on tolerance and love of humankind quickly spread to the masses in Cappadocia, a great center of Christianity, and was adopted by the people. He authored a book entitled Makalat (Articles) in Arabic. Although a religous book, we present a section on embryogenesis of the human being. He states that the bones are created before the visceral organs, and that half of the vessels contain blood, and the other half air, which can be interpreted as venous and arterial vessels.

Anahtar Kelimeler: Hacı Bektaş-ı Veli, embryogenesis, history of pediatrics.