Maurya, kushwaha, shakya etc are basically khhatriya castes as per buddhist tradition. During ancient age they achieved high status in society and were against orthodox superstitious brahmnical religion. Shakyamuni Buddha, Emperor Chandra Gupta Maurya, Ashok Maurya etc were some famous persons of this caste. Anti Buddhist Brahmins made them Sudras to establish their supremacy and their religion. Like retired warriors they chose job of agriculture and especially horticulture.
Maurya, shakya, kushwaha,saini etc were ancient khatriya castes. But shakya/muryan dynasty and its support to buddhism was not acceptable to brahmins as buddhism challenged supremacy of brahmins. Brahmins were educated and were having most of the jobs in royal courts. After fall of mauryans and establishment of brahmin sung dynasty ,they wrote literature describing them sudra and of lower cost. They reestablished brahmnical/hindu religion and gave birth to new caste named rajput which were at that time sudra and tribal castes. Brahmin supported rajputs to establish their kingdoms and promoted them as khatriya. In conclusion maurya, shakya, saini etc. Were aadi khatriya (ancient khatriya).
They are the oldest Kshatriya (rajputra)clan they are decedents of lord Rama. They were ruling Ayodhya in ancient times.Ttheir last king Sumitra was forced to leave Ayodhya by Magadh king Maha padma nand. They were forced do korar (cultivation) for kings .since then probably some of them were called kori/koiroie or kachi as per their occupation or to insult them by kings clan. However some of them who were able reorganize themselves they made their kingdom and hence retained their identity as kushwaha /kshatriya/Rajputra.Rest of the time Kushwahas except Mauryas and Guptas period in Magadh were unable to establish their their kingdom and hence loosing their original identity of kshatriya. In MP, Rajsthan who scattered from Ayodhya were able to make kingdom till rescent history
