Maqam Bayat is one of the most popular and common maqamat in the Arabic repertory. It is also the main maqam in the Bayat Family. Its scale starts with Jins Bayati on the tonic followed by either Jins Nahawand or Jins Rast on the 4th degree.
Maqam Muhayyar is a version of Maqam Bayat whose sayr starts at the octave note (called Muhayyar in the old Arabic scale). Maqam Muhayyar often uses Jins Rast on the forth degree to ascend, then emphasizes Jins Bayati on the octave before descending through the other ajnas common to Maqam Bayat.