Question: In what year was the man who used the pen name "Harun Yahya" born?

Context articles: ʿAbbāsa
The Atlas of Creation
Barmakids
Colin Falconer (writer)
Muhammad Fazal Azim Taha
Adnan Oktar bibliography
Adnan Oktar
Morishima Chūryō
Jane Thayer
Yahya ibn Khalid

ʿAbbāsa was the sister of the caliph Harun al-Rashid and Al-Hadi, and daughter of the caliph Al-Mahdi.
 On the instruction of Harun al-Rashid she had a formal marriage with Ja'far ibn Yahya, a member of the influential Barmakids family and vizier to the caliph.
 Horovitz says that her name is connected with the fall of the Barmakids.
The Atlas of Creation (or, in Turkish, "Yaratılış Atlası") is a series of creationist books written by Adnan Oktar under the pen name "Harun Yahya".
 Oktar published volume 1 of "The Atlas of Creation" with Global Publishing, Istanbul, Turkey in October 2006, volumes 2 and 3 followed in 2007, and volume 4 in 2012.
 The first volume is over 800 pages long.
 The Turkish original was translated into English, German, Chinese, French, Dutch, Italian, Urdu, Hindi and Russian.
The Barmakids (Persian: برمکیان‎ ‎ "Barmakīyān"; Arabic: البرامكة‎ ‎ "al-Barāmikah", from the Sanskrit प्रमुख "pramukha", "leader, chief administrator, registrar"); also spelled Barmecides, were an Iranian influential family from Balkh in Bactria where they were originally hereditary Buddhist leaders (in the Nawbahar monastery), and subsequently came to great political power under the Abbasid caliphs of Baghdad.
 Khalid, the son of Barmak became the prime minister ("wazir") of Al Saffah, the first Caliph of the Abbasid dynasty.
 His son Yahya aided Harun Al-Rashid in capturing the throne and rose to power as the most powerful man in the Caliphate.
 The Barmakids were remarkable for their majesty, splendor and hospitality.
 They are mentioned in some stories of the "Arabian Nights".
Colin Falconer (born 1953) is a pen name of Colin Bowles, who also uses the pen name Mark D'Abranville, an English-born Australian writer.
 Works published under the pen name include contemporary and historical thrillers, and children's books.
 Under his original name he has also published books of satirical fiction; non-fiction books about language; television and radio scripts; and many magazine articles and columns.
Muhammad Fazal Azim Taha (Urdu:حافظ محمد فضل العظیم طہ) is a Pakistani poet, writer, columnist, analyst, tabeeb (physician) and lyricist born on 7 February 1962 in Rawalpindi, Pakistan.
 He started writing poetry in the early 21st century.
 He wrote many poems (Ghazal and Nazam) for children, youth, peace, romance, religious and for the defense of the nation.
 His work for youth has given him popularity and appreciation.
 In response to his work for youth he was given the position of Poet for Youth.
 He has adopted the nickname Taha as his pen name.
 He is the son of Hakeem Muhammad Yahya Khan Shifa who is the master of renowned poet Qateel Shifai.
 Taha also wrote for peace between Pakistan and India.
 Aman Ki Asha is the project of India and Pakistan for the peace of the subcontinent.
 He also Participated in Aman Ki Asha for peace between Pakistan and India.
 This project was started by Jang Media Group (Pakistan) and The Times of India (India).
Following is a list of books written by Turkish author Adnan Oktar (born February 2, 1956), also known by the pen name Harun Yahya.
 Oktar is an advocate of Islamic creationism.
Adnan Oktar (born 2 February 1956), also known as Harun Yahya, is a Turkish author as well as an Islamic creationist.
 In 2007, he sent thousands of unsolicited copies of his book, "The Atlas of Creation", which advocates Islamic creationism, to American scientists, members of Congress, and science museums.
 Oktar runs two organizations of which he is also the Honorary President: "Bilim Araştırma Vakfı" (BAV, literally, "Science Research Foundation", established 1990), which promotes creationism and "Milli Değerleri Koruma Vakfı" (literally, "National Values Preservation Foundation", established 1995) which works domestically on a variety of moral issues.
Morishima Chūryō (森島 中良 , 1756 – December 29, 1810) was an Edo period Japanese author of popular fiction who also wrote a number of works in the field of rangaku (Western studies).
 He wrote under many pen names, including Manzōtei, Shinra Manzō (or, conventionally, Shinra Banshō), and Tenjiku Rōjin ("old man from India").
 The latter constituted an allusion to the pen name Tenjiku Rōnin ("masterless samurai from India"), used by Hiraga Gennai, to whom Chūryō was the principal literary successor.
 Chūryō co-authored several plays with Gennai early in his career, and went on to write in almost all of the many genres of popular fiction that were collectively known as gesaku.
 He also wrote kyōka, or comic waka poetry, under the pen name Taketsue no Sugaru.
 Chūryō was the younger brother of Katsuragawa Hoshū, a shogunal physician and leading scholar of rangaku.
Jane Thayer (the pen name of Catherine Woolley, August 11, 1904 – July 23, 2005) was an American writer.
 She is known best for the book "The Puppy Who Wanted A Boy", which became the basis of a 1980s Saturday Morning cartoon series, "The Puppy's Further Adventures".
 Jane Thayer wrote 86 books for children, many of which ("The Blueberry Pie Elf" and "The Puppy Who Wanted a Boy for Christmas") have become classics.
 She was so prolific that her editor suggested she publish some of her works under a pen name.
 Thus, Catherine authored picture books under the pen name of Jane Thayer, while writing books for older children and adults under her real name.
Yahyā ibn Khālid (Arabic: يحيى بن خالد‎ ‎ ) (died 806 CE ) was a member of the powerful Persian Barmakids family, son of Khalid ibn Barmak.
 Around 765, he was appointed to Azerbaijan by the Caliph Al-Mansur.
 Yahya's son Fadl ibn Yahya was born at Ar-Reiy, at the same time as Caliph al-Mahdi's son Harun.
 Al-Mahdi entrusted Yahya in 778 with Harun's education.