Temporal databases, quickly rising in size, are distinguished by their capacity to maintain the older version of data objects against actions on them, allowing logical deletions. Queries for historical data are particularly costly due to the linear scanning of temporal versions. Temporal data structures like time-split B-Tree or multiversion B-Tree are working underlying the state-of-the-art temporal databases. So far, most efficient temporal data structures are partially persistent or fully persistent, but none of them support Retroactive queries. On the other hand, efficient temporal indexing is required to address bulk loading in a real-life application. To the best of our knowledge, there is no efficient solution for bulk loading and updating Retroactive index structures. This article seeks to offer a new data structure, the Retroactive B-Tree (RBT), to facilitate Retroactive operations in temporal databases as well as bulk loading. It presents theoretical and empirical research and analysis of the suggested data structure and its relevant operations. The experiments were conducted to demonstrate the performance of the proposed Retroactive B-Tree in terms of execution time, I/O complexity, space complexity, and bulk loading. The obtained results show that indexing with a buffer is the most powerful model for existing temporal databases for implementing a Retroactive B-Tree. The tree of lists architecture is observed as an I/O efficient data structure for all variants of temporal indexing for large databases.