that holds a license to use spectrum over Tribal lands and has failed to meet additional construction requirements determined by the Commission under section 6(a)(5), a safe harbor exemption may apply to the third-party licensee, if such licensee has deployed coverage to at least 90 percent of the geographic area over the Tribal lands within its license coverage area. 7. Tribal Broadband Fund (a) In general The Commission shall establish, as an additional universal service support mechanism under section 254 of the Communications Act of 1934 ( 47 U.S.C. 254 ), a mechanism to be known as the Tribal Broadband Fund . The Tribal Broadband Fund shall provide a source of funds for networks and infrastructure buildout over Tribal lands, including support for infrastructure deployment, middle mile and long haul fiber buildout, adoption of digital literacy on Tribal lands, and other related activities to ensure Tribal lands have full access to high-speed wireless broadband services and telecommunications services and other spectrum use. (b) Sources of funding In addition to universal service contributions under section 254(d) of the Communications Act of 1934 ( 47 U.S.C. 254(d) ), the Tribal Broadband Fund shall be funded through proceeds from systems of competitive bidding under section 309(j) of the Communications Act of 1934 ( 47 U.S.C. 309(j) ) (notwithstanding paragraph (8) of such section) and any other accounts or reserve funds available to the Commission, in amounts to be determined under subsection (e). Should the Commission find that the Commission cannot robustly fund the Tribal Broadband Fund from these existing sources, the Commission shall undertake a rulemaking proceeding to determine whether the imposition of additional universal service contributions is necessary to ensure a Tribal Broadband Fund commensurate with the funding need, purposes, and implementation determined pursuant to subsection (e). (c) Prioritization Funding allocations shall be prioritized under the Tribal Broadband Fund where