Shortly after the Earth was formed some 4.54 billion years ago, the emergence of the first microbes took place.  They have been evolving and competing for habitable space ever since, including the human host, us!  However, it has only been since the discovery of the microscope, that we have been able to confirm these occurrences. 

Around 60,000 years ago, H-Pylori migrated out of Africa along with it's human host.  It has remained associated with human hosts since that time.

Despite being identified as early as 1875, the understanding of H-Pylori is still developing.  It wasn't even confirmed to be associated with gastritis or ulcers until the 1980's!  Luckily, Doctors Barry Marshall and Robin Warren discovered the connection, with Marshall even going as far as to infect himself to prove HP could cause such issues!  They later received a Nobel Prize in 2005 for their great contributions to medicine.

  Thank you Dr. Marshall & Dr. Warren!