In order to accomplish simultaneous prebiotic syntheses of all four canonical nucleosides, a new chemical pathway for pyrimidine nucleosides was designed in such a way that it complements that of purine nucleoside reported by the Carell group. More specifically, a nucleophilic pyrimidine precursor is synthesized from a prebiotic molecule called cyanoacetylene. The pyrimidine precursor is subsequently reacted with ribose to establish the N-glycosidic bond. Finally, this ribose-nucleobase precursor conjugate is treated with base under reductive conditions to furnish pyrimidine nucleosides. When this pathway was experimentally investigated, indeed the formation of pyrimidine nucleosides were observed in high yield, thus establishing the simultaneous formation of all canonical nucleosides under plausible prebiotic conditions. In addition to the above mentioned prebiotic synthesis of canonical nucleosides, the potential emergence of non-standard nucleosides which functioned in prebiotic world as a component of early RNA species or proto-RNA was also investigated. In particular, it was speculated that prebiotically available urea derivatives mimic canonical nucleobases by forming intramolecular hydrogen bonds. When these urea derivatives were reacted with ribose under plausible prebiotic conditions, formation of the corresponding nucleoside or pseudo-cyclic pyrimidine nucleosides was observed. These pseudo-cyclic pyrimidine nucleosides were then incorporated into RNA strands using modern synthetic methods to investigate their functions. Remarkably, it was revealed that these non-standard nucleosides form a relatively stable base pair with guanosine in the complementary strands. Taken all together, these results indicate the potential emergence and function of non-standard pseudo-cyclic pyrimidine nucleosides as a component of proto-RNA. In summary, through the PRENUCRNA project we discovered a unified prebiotic pathway for all four canonical nucleosides as well as potential evidence for the emergence and function of non-standard nucleosides on early earth.