All five states mentioned - Uttaranchal (now Uttarakhand), Uttar Pradesh, Bihar, West Bengal, and Sikkim - share their northern borders with Nepal. China shares borders with Uttarakhand, Sikkim, and some other states but not with Uttar Pradesh or Bihar. Bhutan shares borders with West Bengal and Sikkim but not with the other three states. Myanmar shares borders with Northeastern states, not these five.