Taikyo-Ku Shodan aside, the first five katas in the Shotokan syllabus are referred to as the “Heian“.
“Heian” is the combination of two characters. The first (“Hei“) means flat, even, level, calm, ordinary, and peaceful. The next character (“An“) means safe, stable, easy, peaceful, or inexpensive. The word “Heian” is an association of these 2 concepts and is sometimes translated as “Peaceful Mind”.
In fact, the katas were originally known as the “Pinan” (Okinawan pronunciation of the same two characters), but were eventually renamed “Heian” by Funakoshi in an effort to make the art more acceptable in Japan.
The origins of these katas are unclear. However because they are not specific to Shotokan, it is fair to assume they were created before karate reached Japanese mainland. One theory is that the “Pinan” system was put together by Itosu Yasutsune of Shuri City, Okinawa, in the early 20th century, in an effort to teach karate in Okinawan schools. His idea was to devise a system of increasing complexity, culminating in the teaching of Bassai Dai and Kanku Dai. Hence these katas are often seen as having been created from more advanced katas such as Kanku Dai.