If you have large numbers of DWG files that you need to export to a different format (for example, a GIS file format), you can use this tutorial to learn how to export them in bulk. The tutorial explains how to move a folder of DWG files to the SDF format in a single operation.
The examples in this tutorial illustrate batch techniques for exporting, but the same approach can be used to do importing. Also, although the examples use the SDF format, the approach can be used for any file-based format (SHP, DGN, and so on).
The batch-exporting process requires a DOS batch file, an AutoCAD script, and an AutoCAD Map 3D Export profile. While the steps for creating these are included here, you can find additional information on any of these areas:
The batch file loops through the folder in which you stored the DWG files to export. It opens each DWG file it finds. Each iteration runs the script file and renames a temporary file for the current operation.