I know Musashi (武蔵) refers to the old province, but I cannot understand the rest of this sentence. Can anyone help with translation of 國小俳山? Thank you.
小佛山 is the older spelling for 小【こ】仏【ぼとけ】山【やま】 ("Little Buddha Mountain"), which appears to be an older or alternative name for 城山【しろやま】 ("Castle Mountain") in modern-day Kanagawa Prefecture. Japanese Wikipedia article for Shiro-yama, and there doesn't seem to be a corresponding article in English. Also, searching Google Maps for 小仏山 shows results for this same 城山.
PS: Your text seems less like a sentence, and more like a label.