an ▁Buddh ism . ▁Mah ā y ā na ▁was ▁never ▁a ▁separate ▁sect ▁of ▁the ▁early ▁schools . ▁From ▁Chinese ▁mon ks ▁visit ing ▁India , ▁we ▁now ▁know ▁that ▁both ▁Mah ā y ā na ▁and ▁non - M ah ā y ā na ▁mon ks ▁in ▁India ▁often ▁lived ▁in ▁the ▁same ▁monaster ies ▁side ▁by ▁side . ▁ ▁The ▁sevent h - century ▁Chinese ▁Buddh ist ▁mon k ▁and ▁pil gr im ▁Y ij ing ▁wrote ▁about ▁the ▁relationship ▁between ▁the ▁various ▁" ve h icles " ▁and ▁the ▁early ▁Buddh ist ▁schools ▁in ▁India . ▁He ▁wrote , ▁" There ▁exist ▁in ▁the ▁West ▁numerous ▁sub div isions ▁of ▁the ▁schools ▁which ▁have ▁different ▁orig ins , ▁but ▁there ▁are ▁only ▁four ▁principal ▁schools ▁of ▁continuous ▁tradition ." ▁These ▁schools ▁are ▁the ▁Mah ā s ā ṃ gh ika ▁Nik ā ya , ▁S th av ira ▁n ik ā ya , ▁M ū las ar v ā st iv ā da ▁Nik ā ya , ▁and ▁Sa ṃ mit ī ya ▁Nik ā ya . ▁Exp la ining ▁their ▁do ctr inal ▁affili ations , ▁he ▁then ▁writes , ▁" Wh ich ▁of ▁the ▁four ▁schools ▁should ▁be ▁grouped ▁with ▁the ▁Mah ā y ā na ▁or ▁with ▁the ▁H ī n ay ā na ▁is ▁not ▁determined ." ▁That ▁is ▁to ▁say , ▁there ▁was ▁no ▁simple ▁correspond ence ▁between ▁a ▁Buddh ist ▁school ▁and ▁whether ▁its ▁members ▁learn ▁" H ī n ay ā na