YOU SAID:

The rider sat upon the back of his steed eating a fish sandwich

INTO JAPANESE

魚のサンドイッチを食べる彼の馬の後ろに座っていたライダー

BACK INTO ENGLISH

Was sitting behind his fish sandwich to eat horse rider

INTO JAPANESE

馬のライダーを食べる彼の魚のサンドイッチの後ろに座っていた

BACK INTO ENGLISH

Was sitting in the back of the rider of the horse to eat his fish sandwich

INTO JAPANESE

魚サンドイッチを食べ、馬のライダーの後ろに座っていた

BACK INTO ENGLISH

Fish sandwich and was sitting in the back of the horse rider

INTO JAPANESE

魚のサンドイッチと馬のライダーの後ろに座っていた

BACK INTO ENGLISH

Was sitting in the back of the fish sandwich and horse riders

INTO JAPANESE

魚のサンドイッチと馬のライダーの後ろに座っていた

BACK INTO ENGLISH

Was sitting in the back of the fish sandwich and horse riders