The Alchemists in Fullmetal Alchemist use Alchemy for military purposes. It has its own feel and means of practicing. However Alchemy is not the only technique utilized in the anime. Across the desert in the Eastern nation of Xing their version of Alchemy is known as Alkahestry.
Rooted in connection to the Earths energy Alkahestrists use and practice this form in differently compared to to Alchemists. Mei Chang is the only known practicer of Alkahestry in the anime and is Edward and Alphonses teacher on the subject. Alkahestry is also based on real Chinese Philosophy which make the concept interesting to learn about. So what exactly is Alkahestry?
Alkahestry is called Eastern Alchemy practiced by the nation of Xing. It also referred to as Rentanjutsu in the manga. Ling Yao and Mei are royals from this country. Xing is across the Great Desert from Amestris the country of the main characters Ed and Al. Both Ling and Mei travel to Amestris to conduct research on Western Alchemy for their own respective reasons. Xing is made up of over fifty different clans with an emperor ruling the entire nation. A daughter from each clan leader marries the emperor and bears him children. The present emperor has twentyfour sons and nineteen daughters making Ling the twelfth in the line of succession.
Alkahestry is predominantly used in medical practices in Xing. This is a blatant contrast to Amestris where Alchemy is used mainly for war ever since King Bradley became the Führer. Where Amestris view Alchemy as a scientific practice Xing sees Alkahestry as a medicinal form. Mei says that Alkahestry is about reading the Dragons Pulse which humerously confuses Al. This means that it detects and uses the power that flows within the ground. The Earth is viewed as having energy or chi running through it. It is this understanding that roots Eastern Alchemy. The transmission of chi is what allows Alkahestry practices to work.
Where Alchemists use Transmutation Circles Alkahestrists use Purification Circles. These circles allow for chi to flow and fulfill its desired effect. It even permits the transmutations to be projected over long distances a feature unique to Alkahestry.
Alkahestry does have its limits. Eastern Alchemy has not been proven to grant immortality unlike its Western counterpart at least thats what Mei theorizes. This fuels Lings Alchemy research as he is looking for a way to achieve mortality for his father so that he carries favor as the next emperor.